ide-tape: cleanup and fix comments
Also, remove redundant ones and cleanup whitespace.
Bart:
- minor fixups
Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index bdf02fc..d8b02fb 100644
--- a/drivers/ide/ide-tape.c
+++ b/drivers/ide/ide-tape.c
@@ -75,37 +75,34 @@
/*
- * Pipelined mode parameters.
+ * Pipelined mode parameters.
*
- * We try to use the minimum number of stages which is enough to
- * keep the tape constantly streaming. To accomplish that, we implement
- * a feedback loop around the maximum number of stages:
+ * We try to use the minimum number of stages which is enough to keep the tape
+ * constantly streaming. To accomplish that, we implement a feedback loop around
+ * the maximum number of stages:
*
- * We start from MIN maximum stages (we will not even use MIN stages
- * if we don't need them), increment it by RATE*(MAX-MIN)
- * whenever we sense that the pipeline is empty, until we reach
- * the optimum value or until we reach MAX.
+ * We start from MIN maximum stages (we will not even use MIN stages if we don't
+ * need them), increment it by RATE*(MAX-MIN) whenever we sense that the
+ * pipeline is empty, until we reach the optimum value or until we reach MAX.
*
- * Setting the following parameter to 0 is illegal: the pipelined mode
- * cannot be disabled (idetape_calculate_speeds() divides by
- * tape->max_stages.)
+ * Setting the following parameter to 0 is illegal: the pipelined mode cannot be
+ * disabled (idetape_calculate_speeds() divides by tape->max_stages.)
*/
#define IDETAPE_MIN_PIPELINE_STAGES 1
#define IDETAPE_MAX_PIPELINE_STAGES 400
#define IDETAPE_INCREASE_STAGES_RATE 20
/*
- * After each failed packet command we issue a request sense command
- * and retry the packet command IDETAPE_MAX_PC_RETRIES times.
+ * After each failed packet command we issue a request sense command and retry
+ * the packet command IDETAPE_MAX_PC_RETRIES times.
*
- * Setting IDETAPE_MAX_PC_RETRIES to 0 will disable retries.
+ * Setting IDETAPE_MAX_PC_RETRIES to 0 will disable retries.
*/
#define IDETAPE_MAX_PC_RETRIES 3
/*
- * With each packet command, we allocate a buffer of
- * IDETAPE_PC_BUFFER_SIZE bytes. This is used for several packet
- * commands (Not for READ/WRITE commands).
+ * With each packet command, we allocate a buffer of IDETAPE_PC_BUFFER_SIZE
+ * bytes. This is used for several packet commands (Not for READ/WRITE commands)
*/
#define IDETAPE_PC_BUFFER_SIZE 256
@@ -124,48 +121,39 @@
#define IDETAPE_WAIT_CMD (900*HZ)
/*
- * The following parameter is used to select the point in the internal
- * tape fifo in which we will start to refill the buffer. Decreasing
- * the following parameter will improve the system's latency and
- * interactive response, while using a high value might improve system
- * throughput.
+ * The following parameter is used to select the point in the internal tape fifo
+ * in which we will start to refill the buffer. Decreasing the following
+ * parameter will improve the system's latency and interactive response, while
+ * using a high value might improve system throughput.
*/
-#define IDETAPE_FIFO_THRESHOLD 2
+#define IDETAPE_FIFO_THRESHOLD 2
/*
- * DSC polling parameters.
+ * DSC polling parameters.
*
- * Polling for DSC (a single bit in the status register) is a very
- * important function in ide-tape. There are two cases in which we
- * poll for DSC:
+ * Polling for DSC (a single bit in the status register) is a very important
+ * function in ide-tape. There are two cases in which we poll for DSC:
*
- * 1. Before a read/write packet command, to ensure that we
- * can transfer data from/to the tape's data buffers, without
- * causing an actual media access. In case the tape is not
- * ready yet, we take out our request from the device
- * request queue, so that ide.c will service requests from
- * the other device on the same interface meanwhile.
+ * 1. Before a read/write packet command, to ensure that we can transfer data
+ * from/to the tape's data buffers, without causing an actual media access.
+ * In case the tape is not ready yet, we take out our request from the device
+ * request queue, so that ide.c could service requests from the other device
+ * on the same interface in the meantime.
*
- * 2. After the successful initialization of a "media access
- * packet command", which is a command which can take a long
- * time to complete (it can be several seconds or even an hour).
+ * 2. After the successful initialization of a "media access packet command",
+ * which is a command that can take a long time to complete (the interval can
+ * range from several seconds to even an hour). Again, we postpone our request
+ * in the middle to free the bus for the other device. The polling frequency
+ * here should be lower than the read/write frequency since those media access
+ * commands are slow. We start from a "fast" frequency - IDETAPE_DSC_MA_FAST
+ * (1 second), and if we don't receive DSC after IDETAPE_DSC_MA_THRESHOLD
+ * (5 min), we switch it to a lower frequency - IDETAPE_DSC_MA_SLOW (1 min).
*
- * Again, we postpone our request in the middle to free the bus
- * for the other device. The polling frequency here should be
- * lower than the read/write frequency since those media access
- * commands are slow. We start from a "fast" frequency -
- * IDETAPE_DSC_MA_FAST (one second), and if we don't receive DSC
- * after IDETAPE_DSC_MA_THRESHOLD (5 minutes), we switch it to a
- * lower frequency - IDETAPE_DSC_MA_SLOW (1 minute).
- *
- * We also set a timeout for the timer, in case something goes wrong.
- * The timeout should be longer then the maximum execution time of a
- * tape operation.
+ * We also set a timeout for the timer, in case something goes wrong. The
+ * timeout should be longer then the maximum execution time of a tape operation.
*/
-
-/*
- * DSC timings.
- */
+
+/* DSC timings. */
#define IDETAPE_DSC_RW_MIN 5*HZ/100 /* 50 msec */
#define IDETAPE_DSC_RW_MAX 40*HZ/100 /* 400 msec */
#define IDETAPE_DSC_RW_TIMEOUT 2*60*HZ /* 2 minutes */
@@ -176,15 +164,9 @@
/*************************** End of tunable parameters ***********************/
-/*
- * Read/Write error simulation
- */
+/* Read/Write error simulation */
#define SIMULATE_ERRORS 0
-/*
- * For general magnetic tape device compatibility.
- */
-
/* tape directions */
enum {
IDETAPE_DIR_NONE = (1 << 0),
@@ -199,24 +181,32 @@
char *b_data;
};
-/*
- * Our view of a packet command.
- */
typedef struct idetape_packet_command_s {
- u8 c[12]; /* Actual packet bytes */
- int retries; /* On each retry, we increment retries */
- int error; /* Error code */
- int request_transfer; /* Bytes to transfer */
- int actually_transferred; /* Bytes actually transferred */
- int buffer_size; /* Size of our data buffer */
+ /* Actual packet bytes */
+ u8 c[12];
+ /* On each retry, we increment retries */
+ int retries;
+ /* Error code */
+ int error;
+ /* Bytes to transfer */
+ int request_transfer;
+ /* Bytes actually transferred */
+ int actually_transferred;
+ /* Size of our data buffer */
+ int buffer_size;
struct idetape_bh *bh;
char *b_data;
int b_count;
- u8 *buffer; /* Data buffer */
- u8 *current_position; /* Pointer into the above buffer */
- ide_startstop_t (*callback) (ide_drive_t *); /* Called when this packet command is completed */
- u8 pc_buffer[IDETAPE_PC_BUFFER_SIZE]; /* Temporary buffer */
- unsigned long flags; /* Status/Action bit flags: long for set_bit */
+ /* Data buffer */
+ u8 *buffer;
+ /* Pointer into the above buffer */
+ u8 *current_position;
+ /* Called when this packet command is completed */
+ ide_startstop_t (*callback) (ide_drive_t *);
+ /* Temporary buffer */
+ u8 pc_buffer[IDETAPE_PC_BUFFER_SIZE];
+ /* Status/Action bit flags: long for set_bit */
+ unsigned long flags;
} idetape_pc_t;
/*
@@ -235,9 +225,7 @@
/* Data direction */
#define PC_WRITING 5
-/*
- * A pipeline stage.
- */
+/* A pipeline stage. */
typedef struct idetape_stage_s {
struct request rq; /* The corresponding request */
struct idetape_bh *bh; /* The data buffers */
@@ -245,9 +233,8 @@
} idetape_stage_t;
/*
- * Most of our global data which we need to save even as we leave the
- * driver due to an interrupt or a timer event is stored in a variable
- * of type idetape_tape_t, defined below.
+ * Most of our global data which we need to save even as we leave the driver due
+ * to an interrupt or a timer event is stored in the struct defined below.
*/
typedef struct ide_tape_obj {
ide_drive_t *drive;
@@ -283,15 +270,14 @@
int rq_stack_index;
/*
- * DSC polling variables.
+ * DSC polling variables.
*
- * While polling for DSC we use postponed_rq to postpone the
- * current request so that ide.c will be able to service
- * pending requests on the other device. Note that at most
- * we will have only one DSC (usually data transfer) request
- * in the device request queue. Additional requests can be
- * queued in our internal pipeline, but they will be visible
- * to ide.c only one at a time.
+ * While polling for DSC we use postponed_rq to postpone the current
+ * request so that ide.c will be able to service pending requests on the
+ * other device. Note that at most we will have only one DSC (usually
+ * data transfer) request in the device request queue. Additional
+ * requests can be queued in our internal pipeline, but they will be
+ * visible to ide.c only one at a time.
*/
struct request *postponed_rq;
/* The time in which we started polling for DSC */
@@ -303,21 +289,15 @@
unsigned long dsc_poll_freq;
unsigned long dsc_timeout;
- /*
- * Read position information
- */
+ /* Read position information */
u8 partition;
/* Current block */
unsigned int first_frame;
- /*
- * Last error information
- */
+ /* Last error information */
u8 sense_key, asc, ascq;
- /*
- * Character device operation
- */
+ /* Character device operation */
unsigned int minor;
/* device name */
char name[4];
@@ -332,33 +312,30 @@
u8 caps[20];
/*
- * Active data transfer request parameters.
+ * Active data transfer request parameters.
*
- * At most, there is only one ide-tape originated data transfer
- * request in the device request queue. This allows ide.c to
- * easily service requests from the other device when we
- * postpone our active request. In the pipelined operation
- * mode, we use our internal pipeline structure to hold
- * more data requests.
- *
- * The data buffer size is chosen based on the tape's
- * recommendation.
+ * At most, there is only one ide-tape originated data transfer request
+ * in the device request queue. This allows ide.c to easily service
+ * requests from the other device when we postpone our active request.
+ * In the pipelined operation mode, we use our internal pipeline
+ * structure to hold more data requests. The data buffer size is chosen
+ * based on the tape's recommendation.
*/
- /* Ptr to the request which is waiting in the device request queue */
+ /* ptr to the request which is waiting in the device request queue */
struct request *active_data_rq;
- /* Data buffer size (chosen based on the tape's recommendation */
+ /* Data buffer size chosen based on the tape's recommendation */
int stage_size;
idetape_stage_t *merge_stage;
int merge_stage_size;
struct idetape_bh *bh;
char *b_data;
int b_count;
-
+
/*
- * Pipeline parameters.
+ * Pipeline parameters.
*
- * To accomplish non-pipelined mode, we simply set the following
- * variables to zero (or NULL, where appropriate).
+ * To accomplish non-pipelined mode, we simply set the following
+ * variables to zero (or NULL, where appropriate).
*/
/* Number of currently used stages */
int nr_stages;
@@ -385,9 +362,7 @@
/* protects the ide-tape queue */
spinlock_t lock;
- /*
- * Measures average tape speed
- */
+ /* Measures average tape speed */
unsigned long avg_time;
int avg_size;
int avg_speed;
@@ -400,11 +375,9 @@
char write_prot;
/*
- * Limit the number of times a request can
- * be postponed, to avoid an infinite postpone
- * deadlock.
+ * Limit the number of times a request can be postponed, to avoid an
+ * infinite postpone deadlock.
*/
- /* request postpone count limit */
int postpone_cnt;
/*
@@ -419,18 +392,14 @@
int tape_head;
int last_tape_head;
- /*
- * Speed control at the tape buffers input/output
- */
+ /* Speed control at the tape buffers input/output */
unsigned long insert_time;
int insert_size;
int insert_speed;
int max_insert_speed;
int measure_insert_time;
- /*
- * Speed regulation negative feedback loop
- */
+ /* Speed regulation negative feedback loop */
int speed_control;
int pipeline_head_speed;
int controlled_pipeline_head_speed;
@@ -477,9 +446,7 @@
mutex_unlock(&idetape_ref_mutex);
}
-/*
- * Tape door status
- */
+/* Tape door status */
#define DOOR_UNLOCKED 0
#define DOOR_LOCKED 1
#define DOOR_EXPLICITLY_LOCKED 2
@@ -499,30 +466,23 @@
/* 0 = no tape is loaded, so we don't rewind after ejecting */
#define IDETAPE_MEDIUM_PRESENT 9
-/*
- * Some defines for the READ BUFFER command
- */
+/* A define for the READ BUFFER command */
#define IDETAPE_RETRIEVE_FAULTY_BLOCK 6
-/*
- * Some defines for the SPACE command
- */
+/* Some defines for the SPACE command */
#define IDETAPE_SPACE_OVER_FILEMARK 1
#define IDETAPE_SPACE_TO_EOD 3
-/*
- * Some defines for the LOAD UNLOAD command
- */
+/* Some defines for the LOAD UNLOAD command */
#define IDETAPE_LU_LOAD_MASK 1
#define IDETAPE_LU_RETENSION_MASK 2
#define IDETAPE_LU_EOT_MASK 4
/*
- * Special requests for our block device strategy routine.
+ * Special requests for our block device strategy routine.
*
- * In order to service a character device command, we add special
- * requests to the tail of our block device request queue and wait
- * for their completion.
+ * In order to service a character device command, we add special requests to
+ * the tail of our block device request queue and wait for their completion.
*/
enum {
@@ -533,10 +493,7 @@
REQ_IDETAPE_READ_BUFFER = (1 << 4),
};
-/*
- * Error codes which are returned in rq->errors to the higher part
- * of the driver.
- */
+/* Error codes returned in rq->errors to the higher part of the driver. */
#define IDETAPE_ERROR_GENERAL 101
#define IDETAPE_ERROR_FILEMARK 102
#define IDETAPE_ERROR_EOD 103
@@ -560,8 +517,8 @@
#define IDETAPE_CAPABILITIES_PAGE 0x2a
/*
- * The variables below are used for the character device interface.
- * Additional state variables are defined in our ide_drive_t structure.
+ * The variables below are used for the character device interface. Additional
+ * state variables are defined in our ide_drive_t structure.
*/
static struct ide_tape_obj * idetape_devs[MAX_HWIFS * MAX_DRIVES];
@@ -579,10 +536,6 @@
return tape;
}
-/*
- * Function declarations
- *
- */
static int idetape_chrdev_release (struct inode *inode, struct file *filp);
static void idetape_write_release (ide_drive_t *drive, unsigned int minor);
@@ -711,9 +664,6 @@
return (&tape->rq_stack[tape->rq_stack_index++]);
}
-/*
- * idetape_init_pc initializes a packet command.
- */
static void idetape_init_pc (idetape_pc_t *pc)
{
memset(pc->c, 0, 12);
@@ -809,10 +759,7 @@
tape->next_stage = stage->next;
}
-/*
- * idetape_kfree_stage calls kfree to completely free a stage, along with
- * its related buffers.
- */
+/* Free a stage along with its related buffers completely. */
static void __idetape_kfree_stage (idetape_stage_t *stage)
{
struct idetape_bh *prev_bh, *bh = stage->bh;
@@ -840,8 +787,8 @@
}
/*
- * idetape_remove_stage_head removes tape->first_stage from the pipeline.
- * The caller should avoid race conditions.
+ * Remove tape->first_stage from the pipeline. The caller should avoid race
+ * conditions.
*/
static void idetape_remove_stage_head (ide_drive_t *drive)
{
@@ -899,8 +846,8 @@
}
/*
- * idetape_end_request is used to finish servicing a request, and to
- * insert a pending pipeline request into the main device queue.
+ * Finish servicing a request and insert a pending pipeline request into the
+ * main device queue.
*/
static int idetape_end_request(ide_drive_t *drive, int uptodate, int nr_sects)
{
@@ -951,9 +898,7 @@
if (tape->next_stage != NULL) {
idetape_activate_next_stage(drive);
- /*
- * Insert the next request into the request queue.
- */
+ /* Insert the next request into the request queue. */
(void)ide_do_drive_cmd(drive, tape->active_data_rq,
ide_end);
} else if (!error) {
@@ -1020,23 +965,19 @@
}
/*
- * idetape_queue_pc_head generates a new packet command request in front
- * of the request queue, before the current request, so that it will be
- * processed immediately, on the next pass through the driver.
+ * Generate a new packet command request in front of the request queue, before
+ * the current request, so that it will be processed immediately, on the next
+ * pass through the driver. The function below is called from the request
+ * handling part of the driver (the "bottom" part). Safe storage for the request
+ * should be allocated with ide_tape_next_{pc,rq}_storage() prior to that.
*
- * idetape_queue_pc_head is called from the request handling part of
- * the driver (the "bottom" part). Safe storage for the request should
- * be allocated with idetape_next_pc_storage and idetape_next_rq_storage
- * before calling idetape_queue_pc_head.
+ * Memory for those requests is pre-allocated at initialization time, and is
+ * limited to IDETAPE_PC_STACK requests. We assume that we have enough space for
+ * the maximum possible number of inter-dependent packet commands.
*
- * Memory for those requests is pre-allocated at initialization time, and
- * is limited to IDETAPE_PC_STACK requests. We assume that we have enough
- * space for the maximum possible number of inter-dependent packet commands.
- *
- * The higher level of the driver - The ioctl handler and the character
- * device handling functions should queue request to the lower level part
- * and wait for their completion using idetape_queue_pc_tail or
- * idetape_queue_rw_tail.
+ * The higher level of the driver - The ioctl handler and the character device
+ * handling functions should queue request to the lower level part and wait for
+ * their completion using idetape_queue_pc_tail or idetape_queue_rw_tail.
*/
static void idetape_queue_pc_head (ide_drive_t *drive, idetape_pc_t *pc,struct request *rq)
{
@@ -1069,9 +1010,8 @@
}
/*
- * idetape_postpone_request postpones the current request so that
- * ide.c will be able to service requests from another device on
- * the same hwgroup while we are polling for DSC.
+ * Postpone the current request so that ide.c will be able to service requests
+ * from another device on the same hwgroup while we are polling for DSC.
*/
static void idetape_postpone_request (ide_drive_t *drive)
{
@@ -1258,46 +1198,40 @@
}
/*
- * Packet Command Interface
+ * Packet Command Interface
*
- * The current Packet Command is available in tape->pc, and will not
- * change until we finish handling it. Each packet command is associated
- * with a callback function that will be called when the command is
- * finished.
+ * The current Packet Command is available in tape->pc, and will not change
+ * until we finish handling it. Each packet command is associated with a
+ * callback function that will be called when the command is finished.
*
- * The handling will be done in three stages:
+ * The handling will be done in three stages:
*
- * 1. idetape_issue_pc will send the packet command to the
- * drive, and will set the interrupt handler to idetape_pc_intr.
+ * 1. idetape_issue_pc will send the packet command to the drive, and will set
+ * the interrupt handler to idetape_pc_intr.
*
- * 2. On each interrupt, idetape_pc_intr will be called. This step
- * will be repeated until the device signals us that no more
- * interrupts will be issued.
+ * 2. On each interrupt, idetape_pc_intr will be called. This step will be
+ * repeated until the device signals us that no more interrupts will be issued.
*
- * 3. ATAPI Tape media access commands have immediate status with a
- * delayed process. In case of a successful initiation of a
- * media access packet command, the DSC bit will be set when the
- * actual execution of the command is finished.
- * Since the tape drive will not issue an interrupt, we have to
- * poll for this event. In this case, we define the request as
- * "low priority request" by setting rq_status to
- * IDETAPE_RQ_POSTPONED, set a timer to poll for DSC and exit
- * the driver.
+ * 3. ATAPI Tape media access commands have immediate status with a delayed
+ * process. In case of a successful initiation of a media access packet command,
+ * the DSC bit will be set when the actual execution of the command is finished.
+ * Since the tape drive will not issue an interrupt, we have to poll for this
+ * event. In this case, we define the request as "low priority request" by
+ * setting rq_status to IDETAPE_RQ_POSTPONED, set a timer to poll for DSC and
+ * exit the driver.
*
- * ide.c will then give higher priority to requests which
- * originate from the other device, until will change rq_status
- * to RQ_ACTIVE.
+ * ide.c will then give higher priority to requests which originate from the
+ * other device, until will change rq_status to RQ_ACTIVE.
*
- * 4. When the packet command is finished, it will be checked for errors.
+ * 4. When the packet command is finished, it will be checked for errors.
*
- * 5. In case an error was found, we queue a request sense packet
- * command in front of the request queue and retry the operation
- * up to IDETAPE_MAX_PC_RETRIES times.
+ * 5. In case an error was found, we queue a request sense packet command in
+ * front of the request queue and retry the operation up to
+ * IDETAPE_MAX_PC_RETRIES times.
*
- * 6. In case no error was found, or we decided to give up and not
- * to retry again, the callback function will be called and then
- * we will handle the next request.
- *
+ * 6. In case no error was found, or we decided to give up and not to retry
+ * again, the callback function will be called and then we will handle the next
+ * request.
*/
static ide_startstop_t idetape_transfer_pc(ide_drive_t *drive)
{
@@ -1363,9 +1297,9 @@
if (pc->retries > IDETAPE_MAX_PC_RETRIES ||
test_bit(PC_ABORT, &pc->flags)) {
/*
- * We will "abort" retrying a packet command in case
- * a legitimate error code was received (crossing a
- * filemark, or end of the media, for example).
+ * We will "abort" retrying a packet command in case legitimate
+ * error code was received (crossing a filemark, or end of the
+ * media, for example).
*/
if (!test_bit(PC_ABORT, &pc->flags)) {
if (!(pc->c[0] == TEST_UNIT_READY &&
@@ -1416,9 +1350,6 @@
}
}
-/*
- * General packet command callback function.
- */
static ide_startstop_t idetape_pc_callback (ide_drive_t *drive)
{
idetape_tape_t *tape = drive->driver_data;
@@ -1429,15 +1360,14 @@
return ide_stopped;
}
-/*
- * A mode sense command is used to "sense" tape parameters.
- */
+/* A mode sense command is used to "sense" tape parameters. */
static void idetape_create_mode_sense_cmd (idetape_pc_t *pc, u8 page_code)
{
idetape_init_pc(pc);
pc->c[0] = MODE_SENSE;
if (page_code != IDETAPE_BLOCK_DESCRIPTOR)
- pc->c[1] = 8; /* DBD = 1 - Don't return block descriptors */
+ /* DBD = 1 - Don't return block descriptors */
+ pc->c[1] = 8;
pc->c[2] = page_code;
/*
* Changed pc->c[3] to 0 (255 will at best return unused info).
@@ -1447,7 +1377,8 @@
* and return an error when 255 is used.
*/
pc->c[3] = 0;
- pc->c[4] = 255; /* (We will just discard data in that case) */
+ /* We will just discard data in that case */
+ pc->c[4] = 255;
if (page_code == IDETAPE_BLOCK_DESCRIPTOR)
pc->request_transfer = 12;
else if (page_code == IDETAPE_CAPABILITIES_PAGE)
@@ -1619,9 +1550,6 @@
set_bit(PC_DMA_RECOMMENDED, &pc->flags);
}
-/*
- * idetape_do_request is our request handling function.
- */
static ide_startstop_t idetape_do_request(ide_drive_t *drive,
struct request *rq, sector_t block)
{
@@ -1635,18 +1563,14 @@
rq->sector, rq->nr_sectors, rq->current_nr_sectors);
if (!blk_special_request(rq)) {
- /*
- * We do not support buffer cache originated requests.
- */
+ /* We do not support buffer cache originated requests. */
printk(KERN_NOTICE "ide-tape: %s: Unsupported request in "
"request queue (%d)\n", drive->name, rq->cmd_type);
ide_end_request(drive, 0, 0);
return ide_stopped;
}
- /*
- * Retry a failed packet command
- */
+ /* Retry a failed packet command */
if (tape->failed_pc != NULL &&
tape->pc->c[0] == REQUEST_SENSE) {
return idetape_issue_pc(drive, tape->failed_pc);
@@ -1733,9 +1657,7 @@
return idetape_issue_pc(drive, pc);
}
-/*
- * Pipeline related functions
- */
+/* Pipeline related functions */
static inline int idetape_pipeline_active (idetape_tape_t *tape)
{
int rc1, rc2;
@@ -1746,16 +1668,16 @@
}
/*
- * idetape_kmalloc_stage uses __get_free_page to allocate a pipeline
- * stage, along with all the necessary small buffers which together make
- * a buffer of size tape->stage_size (or a bit more). We attempt to
- * combine sequential pages as much as possible.
+ * The function below uses __get_free_page to allocate a pipeline stage, along
+ * with all the necessary small buffers which together make a buffer of size
+ * tape->stage_size (or a bit more). We attempt to combine sequential pages as
+ * much as possible.
*
- * Returns a pointer to the new allocated stage, or NULL if we
- * can't (or don't want to) allocate a stage.
+ * It returns a pointer to the new allocated stage, or NULL if we can't (or
+ * don't want to) allocate a stage.
*
- * Pipeline stages are optional and are used to increase performance.
- * If we can't allocate them, we'll manage without them.
+ * Pipeline stages are optional and are used to increase performance. If we
+ * can't allocate them, we'll manage without them.
*/
static idetape_stage_t *__idetape_kmalloc_stage (idetape_tape_t *tape, int full, int clear)
{
@@ -1913,9 +1835,7 @@
idetape_init_merge_stage(tape);
}
-/*
- * idetape_add_stage_tail adds a new stage at the end of the pipeline.
- */
+/* Add a new stage at the end of the pipeline. */
static void idetape_add_stage_tail (ide_drive_t *drive,idetape_stage_t *stage)
{
idetape_tape_t *tape = drive->driver_data;
@@ -1937,12 +1857,9 @@
spin_unlock_irqrestore(&tape->lock, flags);
}
-/*
- * idetape_wait_for_request installs a completion in a pending request
- * and sleeps until it is serviced.
- *
- * The caller should ensure that the request will not be serviced
- * before we install the completion (usually by disabling interrupts).
+/* Install a completion in a pending request and sleep until it is serviced. The
+ * caller should ensure that the request will not be serviced before we install
+ * the completion (usually by disabling interrupts).
*/
static void idetape_wait_for_request (ide_drive_t *drive, struct request *rq)
{
@@ -1996,12 +1913,8 @@
}
/*
- * idetape_create_write_filemark_cmd will:
- *
- * 1. Write a filemark if write_filemark=1.
- * 2. Flush the device buffers without writing a filemark
- * if write_filemark=0.
- *
+ * Write a filemark if write_filemark=1. Flush the device buffers without
+ * writing a filemark otherwise.
*/
static void idetape_create_write_filemark_cmd (ide_drive_t *drive, idetape_pc_t *pc,int write_filemark)
{
@@ -2020,24 +1933,17 @@
}
/*
- * idetape_queue_pc_tail is based on the following functions:
+ * We add a special packet command request to the tail of the request queue, and
+ * wait for it to be serviced. This is not to be called from within the request
+ * handling part of the driver! We allocate here data on the stack and it is
+ * valid until the request is finished. This is not the case for the bottom part
+ * of the driver, where we are always leaving the functions to wait for an
+ * interrupt or a timer event.
*
- * ide_do_drive_cmd from ide.c
- * cdrom_queue_request and cdrom_queue_packet_command from ide-cd.c
- *
- * We add a special packet command request to the tail of the request
- * queue, and wait for it to be serviced.
- *
- * This is not to be called from within the request handling part
- * of the driver ! We allocate here data in the stack, and it is valid
- * until the request is finished. This is not the case for the bottom
- * part of the driver, where we are always leaving the functions to wait
- * for an interrupt or a timer event.
- *
- * From the bottom part of the driver, we should allocate safe memory
- * using idetape_next_pc_storage and idetape_next_rq_storage, and add
- * the request to the request list without waiting for it to be serviced !
- * In that case, we usually use idetape_queue_pc_head.
+ * From the bottom part of the driver, we should allocate safe memory using
+ * idetape_next_pc_storage() and ide_tape_next_rq_storage(), and add the request
+ * to the request list without waiting for it to be serviced! In that case, we
+ * usually use idetape_queue_pc_head().
*/
static int __idetape_queue_pc_tail (ide_drive_t *drive, idetape_pc_t *pc)
{
@@ -2065,9 +1971,7 @@
idetape_pc_t pc;
int load_attempted = 0;
- /*
- * Wait for the tape to become ready
- */
+ /* Wait for the tape to become ready */
set_bit(IDETAPE_MEDIUM_PRESENT, &tape->flags);
timeout += jiffies;
while (time_before(jiffies, timeout)) {
@@ -2075,7 +1979,8 @@
if (!__idetape_queue_pc_tail(drive, &pc))
return 0;
if ((tape->sense_key == 2 && tape->asc == 4 && tape->ascq == 2)
- || (tape->asc == 0x3A)) { /* no media */
+ || (tape->asc == 0x3A)) {
+ /* no media */
if (load_attempted)
return -ENOMEDIUM;
idetape_create_load_unload_cmd(drive, &pc, IDETAPE_LU_LOAD_MASK);
@@ -2203,13 +2108,10 @@
}
/*
- * idetape_position_tape positions the tape to the requested block
- * using the LOCATE packet command. A READ POSITION command is then
- * issued to check where we are positioned.
- *
- * Like all higher level operations, we queue the commands at the tail
- * of the request queue and wait for their completion.
- *
+ * Position the tape to the requested block using the LOCATE packet command.
+ * A READ POSITION command is then issued to check where we are positioned. Like
+ * all higher level operations, we queue the commands at the tail of the request
+ * queue and wait for their completion.
*/
static int idetape_position_tape (ide_drive_t *drive, unsigned int block, u8 partition, int skip)
{
@@ -2247,8 +2149,8 @@
}
/*
- * idetape_queue_rw_tail generates a read/write request for the block
- * device interface and wait for it to be serviced.
+ * Generate a read/write request for the block device interface and wait for it
+ * to be serviced.
*/
static int idetape_queue_rw_tail(ide_drive_t *drive, int cmd, int blocks, struct idetape_bh *bh)
{
@@ -2343,15 +2245,15 @@
}
/*
- * idetape_add_chrdev_write_request tries to add a character device
- * originated write request to our pipeline. In case we don't succeed,
- * we revert to non-pipelined operation mode for this request.
+ * Try to add a character device originated write request to our pipeline. In
+ * case we don't succeed, we revert to non-pipelined operation mode for this
+ * request. In order to accomplish that, we
*
- * 1. Try to allocate a new pipeline stage.
- * 2. If we can't, wait for more and more requests to be serviced
- * and try again each time.
- * 3. If we still can't allocate a stage, fallback to
- * non-pipelined operation mode for this request.
+ * 1. Try to allocate a new pipeline stage.
+ * 2. If we can't, wait for more and more requests to be serviced and try again
+ * each time.
+ * 3. If we still can't allocate a stage, fallback to non-pipelined operation
+ * mode for this request.
*/
static int idetape_add_chrdev_write_request (ide_drive_t *drive, int blocks)
{
@@ -2362,10 +2264,7 @@
debug_log(DBG_CHRDEV, "Enter %s\n", __func__);
- /*
- * Attempt to allocate a new stage.
- * Pay special attention to possible race conditions.
- */
+ /* Attempt to allocate a new stage. Beware possible race conditions. */
while ((new_stage = idetape_kmalloc_stage(tape)) == NULL) {
spin_lock_irqsave(&tape->lock, flags);
if (idetape_pipeline_active(tape)) {
@@ -2377,8 +2276,8 @@
if (idetape_pipeline_active(tape))
continue;
/*
- * Linux is short on memory. Fallback to
- * non-pipelined operation mode for this request.
+ * The machine is short on memory. Fallback to non-
+ * pipelined operation mode for this request.
*/
return idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, blocks, tape->merge_stage->bh);
}
@@ -2395,11 +2294,11 @@
idetape_calculate_speeds(drive);
/*
- * Estimate whether the tape has stopped writing by checking
- * if our write pipeline is currently empty. If we are not
- * writing anymore, wait for the pipeline to be full enough
- * (90%) before starting to service requests, so that we will
- * be able to keep up with the higher speeds of the tape.
+ * Estimate whether the tape has stopped writing by checking if our
+ * write pipeline is currently empty. If we are not writing anymore,
+ * wait for the pipeline to be almost completely full (90%) before
+ * starting to service requests, so that we will be able to keep up with
+ * the higher speeds of the tape.
*/
if (!idetape_pipeline_active(tape)) {
if (tape->nr_stages >= tape->max_stages * 9 / 10 ||
@@ -2420,8 +2319,8 @@
}
/*
- * idetape_wait_for_pipeline will wait until all pending pipeline
- * requests are serviced. Typically called on device close.
+ * Wait until all pending pipeline requests are serviced. Typically called on
+ * device close.
*/
static void idetape_wait_for_pipeline (ide_drive_t *drive)
{
@@ -2490,10 +2389,10 @@
tape->chrdev_dir = IDETAPE_DIR_NONE;
/*
- * On the next backup, perform the feedback loop again.
- * (I don't want to keep sense information between backups,
- * as some systems are constantly on, and the system load
- * can be totally different on the next backup).
+ * On the next backup, perform the feedback loop again. (I don't want to
+ * keep sense information between backups, as some systems are
+ * constantly on, and the system load can be totally different on the
+ * next backup).
*/
tape->max_stages = tape->min_pipeline;
if (tape->first_stage != NULL ||
@@ -2545,11 +2444,10 @@
tape->chrdev_dir = IDETAPE_DIR_READ;
/*
- * Issue a read 0 command to ensure that DSC handshake
- * is switched from completion mode to buffer available
- * mode.
- * No point in issuing this if DSC overlap isn't supported,
- * some drives (Seagate STT3401A) will return an error.
+ * Issue a read 0 command to ensure that DSC handshake is
+ * switched from completion mode to buffer available mode.
+ * No point in issuing this if DSC overlap isn't supported, some
+ * drives (Seagate STT3401A) will return an error.
*/
if (drive->dsc_overlap) {
bytes_read = idetape_queue_rw_tail(drive, REQ_IDETAPE_READ, 0, tape->merge_stage->bh);
@@ -2590,9 +2488,8 @@
}
/*
- * idetape_add_chrdev_read_request is called from idetape_chrdev_read
- * to service a character device read request and add read-ahead
- * requests to our pipeline.
+ * Called from idetape_chrdev_read() to service a character device read request
+ * and add read-ahead requests to our pipeline.
*/
static int idetape_add_chrdev_read_request (ide_drive_t *drive,int blocks)
{
@@ -2603,16 +2500,11 @@
debug_log(DBG_PROCS, "Enter %s, %d blocks\n", __func__, blocks);
- /*
- * If we are at a filemark, return a read length of 0
- */
+ /* If we are at a filemark, return a read length of 0 */
if (test_bit(IDETAPE_FILEMARK, &tape->flags))
return 0;
- /*
- * Wait for the next block to be available at the head
- * of the pipeline
- */
+ /* Wait for the next block to reach the head of the pipeline. */
idetape_init_read(drive, tape->max_stages);
if (tape->first_stage == NULL) {
if (test_bit(IDETAPE_PIPELINE_ERROR, &tape->flags))
@@ -2651,7 +2543,7 @@
idetape_tape_t *tape = drive->driver_data;
struct idetape_bh *bh;
int blocks;
-
+
while (bcount) {
unsigned int count;
@@ -2691,10 +2583,9 @@
}
/*
- * Rewinds the tape to the Beginning Of the current Partition (BOP).
- *
- * We currently support only one partition.
- */
+ * Rewinds the tape to the Beginning Of the current Partition (BOP). We
+ * currently support only one partition.
+ */
static int idetape_rewind_tape (ide_drive_t *drive)
{
int retval;
@@ -2716,13 +2607,7 @@
return 0;
}
-/*
- * Our special ide-tape ioctl's.
- *
- * Currently there aren't any ioctl's.
- * mtio.h compatible commands should be issued to the character device
- * interface.
- */
+/* mtio.h compatible commands should be issued to the chrdev interface. */
static int idetape_blkdev_ioctl(ide_drive_t *drive, unsigned int cmd, unsigned long arg)
{
idetape_tape_t *tape = drive->driver_data;
@@ -2756,13 +2641,11 @@
}
/*
- * idetape_space_over_filemarks is now a bit more complicated than just
- * passing the command to the tape since we may have crossed some
- * filemarks during our pipelined read-ahead mode.
- *
- * As a minor side effect, the pipeline enables us to support MTFSFM when
- * the filemark is in our internal pipeline even if the tape doesn't
- * support spacing over filemarks in the reverse direction.
+ * The function below is now a bit more complicated than just passing the
+ * command to the tape since we may have crossed some filemarks during our
+ * pipelined read-ahead mode. As a minor side effect, the pipeline enables us to
+ * support MTFSFM when the filemark is in our internal pipeline even if the tape
+ * doesn't support spacing over filemarks in the reverse direction.
*/
static int idetape_space_over_filemarks (ide_drive_t *drive,short mt_op,int mt_count)
{
@@ -2781,10 +2664,7 @@
}
if (tape->chrdev_dir == IDETAPE_DIR_READ) {
- /*
- * We have a read-ahead buffer. Scan it for crossed
- * filemarks.
- */
+ /* its a read-ahead buffer, scan it for crossed filemarks. */
tape->merge_stage_size = 0;
if (test_and_clear_bit(IDETAPE_FILEMARK, &tape->flags))
++count;
@@ -2797,13 +2677,15 @@
spin_lock_irqsave(&tape->lock, flags);
if (tape->first_stage == tape->active_stage) {
/*
- * We have reached the active stage in the read pipeline.
- * There is no point in allowing the drive to continue
- * reading any farther, so we stop the pipeline.
+ * We have reached the active stage in the read
+ * pipeline. There is no point in allowing the
+ * drive to continue reading any farther, so we
+ * stop the pipeline.
*
- * This section should be moved to a separate subroutine,
- * because a similar function is performed in
- * __idetape_discard_read_pipeline(), for example.
+ * This section should be moved to a separate
+ * subroutine because similar operations are
+ * done in __idetape_discard_read_pipeline(),
+ * for example.
*/
tape->next_stage = NULL;
spin_unlock_irqrestore(&tape->lock, flags);
@@ -2819,8 +2701,8 @@
}
/*
- * The filemark was not found in our internal pipeline.
- * Now we can issue the space command.
+ * The filemark was not found in our internal pipeline; now we can issue
+ * the space command.
*/
switch (mt_op) {
case MTFSF:
@@ -2843,21 +2725,19 @@
/*
- * Our character device read / write functions.
+ * Our character device read / write functions.
*
- * The tape is optimized to maximize throughput when it is transferring
- * an integral number of the "continuous transfer limit", which is
- * a parameter of the specific tape (26 KB on my particular tape).
- * (32 kB for Onstream)
+ * The tape is optimized to maximize throughput when it is transferring an
+ * integral number of the "continuous transfer limit", which is a parameter of
+ * the specific tape (26kB on my particular tape, 32kB for Onstream).
*
- * As of version 1.3 of the driver, the character device provides an
- * abstract continuous view of the media - any mix of block sizes (even 1
- * byte) on the same backup/restore procedure is supported. The driver
- * will internally convert the requests to the recommended transfer unit,
- * so that an unmatch between the user's block size to the recommended
- * size will only result in a (slightly) increased driver overhead, but
- * will no longer hit performance.
- * This is not applicable to Onstream.
+ * As of version 1.3 of the driver, the character device provides an abstract
+ * continuous view of the media - any mix of block sizes (even 1 byte) on the
+ * same backup/restore procedure is supported. The driver will internally
+ * convert the requests to the recommended transfer unit, so that an unmatch
+ * between the user's block size to the recommended size will only result in a
+ * (slightly) increased driver overhead, but will no longer hit performance.
+ * This is not applicable to Onstream.
*/
static ssize_t idetape_chrdev_read (struct file *file, char __user *buf,
size_t count, loff_t *ppos)
@@ -2950,11 +2830,10 @@
idetape_init_merge_stage(tape);
/*
- * Issue a write 0 command to ensure that DSC handshake
- * is switched from completion mode to buffer available
- * mode.
- * No point in issuing this if DSC overlap isn't supported,
- * some drives (Seagate STT3401A) will return an error.
+ * Issue a write 0 command to ensure that DSC handshake is
+ * switched from completion mode to buffer available mode. No
+ * point in issuing this if DSC overlap isn't supported, some
+ * drives (Seagate STT3401A) will return an error.
*/
if (drive->dsc_overlap) {
ssize_t retval = idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, 0, tape->merge_stage->bh);
@@ -3045,9 +2924,7 @@
debug_log(DBG_ERR, "Handling MTIOCTOP ioctl: mt_op=%d, mt_count=%d\n",
mt_op, mt_count);
- /*
- * Commands which need our pipelined read-ahead stages.
- */
+ /* Commands which need our pipelined read-ahead stages. */
switch (mt_op) {
case MTFSF:
case MTFSFM:
@@ -3235,9 +3112,6 @@
tape->drv_write_prot = (pc.buffer[2] & 0x80) >> 7;
}
-/*
- * Our character device open function.
- */
static int idetape_chrdev_open (struct inode *inode, struct file *filp)
{
unsigned int minor = iminor(inode), i = minor & ~0xc0;
@@ -3304,9 +3178,7 @@
}
}
- /*
- * Lock the tape drive door so user can't eject.
- */
+ /* Lock the tape drive door so user can't eject. */
if (tape->chrdev_dir == IDETAPE_DIR_NONE) {
if (idetape_create_prevent_cmd(drive, &pc, 1)) {
if (!idetape_queue_pc_tail(drive, &pc)) {
@@ -3341,9 +3213,6 @@
idetape_flush_tape_buffers(drive);
}
-/*
- * Our character device release function.
- */
static int idetape_chrdev_release (struct inode *inode, struct file *filp)
{
struct ide_tape_obj *tape = ide_tape_f(filp);
@@ -3500,9 +3369,6 @@
{
idetape_tape_t *tape = drive->driver_data;
-/*
- * drive setting name read/write data type min max mul_factor div_factor data pointer set function
- */
ide_add_setting(drive, "buffer", SETTING_READ, TYPE_SHORT, 0, 0xffff,
1, 2, (u16 *)&tape->caps[16], NULL);
ide_add_setting(drive, "pipeline_min", SETTING_RW, TYPE_INT, 1, 0xffff, tape->stage_size / 1024, 1, &tape->min_pipeline, NULL);
@@ -3529,16 +3395,15 @@
#endif
/*
- * ide_setup is called to:
+ * The function below is called to:
*
- * 1. Initialize our various state variables.
- * 2. Ask the tape for its capabilities.
- * 3. Allocate a buffer which will be used for data
- * transfer. The buffer size is chosen based on
- * the recommendation which we received in step (2).
+ * 1. Initialize our various state variables.
+ * 2. Ask the tape for its capabilities.
+ * 3. Allocate a buffer which will be used for data transfer. The buffer size
+ * is chosen based on the recommendation which we received in step 2.
*
- * Note that at this point ide.c already assigned us an irq, so that
- * we can queue requests here and wait for their completion.
+ * Note that at this point ide.c already assigned us an irq, so that we can
+ * queue requests here and wait for their completion.
*/
static void idetape_setup (ide_drive_t *drive, idetape_tape_t *tape, int minor)
{
@@ -3572,7 +3437,7 @@
set_bit(IDETAPE_DRQ_INTERRUPT, &tape->flags);
tape->min_pipeline = tape->max_pipeline = tape->max_stages = 10;
-
+
idetape_get_inquiry_results(drive);
idetape_get_mode_sense_results(drive);
ide_tape_get_bsize_from_bdesc(drive);
@@ -3595,9 +3460,7 @@
tape->max_stages = speed * 1000 * 10 / tape->stage_size;
- /*
- * Limit memory use for pipeline to 10% of physical memory
- */
+ /* Limit memory use for pipeline to 10% of physical memory */
si_meminfo(&si);
if (tape->max_stages * tape->stage_size > si.totalram * si.mem_unit / 10)
tape->max_stages = si.totalram * si.mem_unit / (10 * tape->stage_size);
@@ -3617,8 +3480,8 @@
t = t1;
/*
- * Ensure that the number we got makes sense; limit
- * it within IDETAPE_DSC_RW_MIN and IDETAPE_DSC_RW_MAX.
+ * Ensure that the number we got makes sense; limit it within
+ * IDETAPE_DSC_RW_MIN and IDETAPE_DSC_RW_MAX.
*/
tape->best_dsc_rw_freq = max_t(unsigned long,
min_t(unsigned long, t, IDETAPE_DSC_RW_MAX),
@@ -3706,9 +3569,7 @@
#endif
};
-/*
- * Our character device supporting functions, passed to register_chrdev.
- */
+/* Our character device supporting functions, passed to register_chrdev. */
static const struct file_operations idetape_fops = {
.owner = THIS_MODULE,
.read = idetape_chrdev_read,