[S390] tape: deadlock on system work queue
The 34xx and 3590 tape driver uses the system work queue to defer work
from the interrupt function to process context, e.g. a medium sense
after an unsolicited interrupt. The tape commands started by the work
handler need to be asynchronous, otherwise a deadlock on the system
work queue can occur.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/char/tape.h b/drivers/s390/char/tape.h
index 7a242f0..267b54e 100644
--- a/drivers/s390/char/tape.h
+++ b/drivers/s390/char/tape.h
@@ -280,6 +280,14 @@
return rc;
}
+static inline void
+tape_do_io_async_free(struct tape_device *device, struct tape_request *request)
+{
+ request->callback = (void *) tape_free_request;
+ request->callback_data = NULL;
+ tape_do_io_async(device, request);
+}
+
extern int tape_oper_handler(int irq, int status);
extern void tape_noper_handler(int irq, int status);
extern int tape_open(struct tape_device *);
diff --git a/drivers/s390/char/tape_34xx.c b/drivers/s390/char/tape_34xx.c
index c17f35b..c265111 100644
--- a/drivers/s390/char/tape_34xx.c
+++ b/drivers/s390/char/tape_34xx.c
@@ -53,23 +53,11 @@
* Medium sense for 34xx tapes. There is no 'real' medium sense call.
* So we just do a normal sense.
*/
-static int
-tape_34xx_medium_sense(struct tape_device *device)
+static void __tape_34xx_medium_sense(struct tape_request *request)
{
- struct tape_request *request;
- unsigned char *sense;
- int rc;
+ struct tape_device *device = request->device;
+ unsigned char *sense;
- request = tape_alloc_request(1, 32);
- if (IS_ERR(request)) {
- DBF_EXCEPTION(6, "MSEN fail\n");
- return PTR_ERR(request);
- }
-
- request->op = TO_MSEN;
- tape_ccw_end(request->cpaddr, SENSE, 32, request->cpdata);
-
- rc = tape_do_io_interruptible(device, request);
if (request->rc == 0) {
sense = request->cpdata;
@@ -88,15 +76,47 @@
device->tape_generic_status |= GMT_WR_PROT(~0);
else
device->tape_generic_status &= ~GMT_WR_PROT(~0);
- } else {
+ } else
DBF_EVENT(4, "tape_34xx: medium sense failed with rc=%d\n",
request->rc);
- }
tape_free_request(request);
+}
+static int tape_34xx_medium_sense(struct tape_device *device)
+{
+ struct tape_request *request;
+ int rc;
+
+ request = tape_alloc_request(1, 32);
+ if (IS_ERR(request)) {
+ DBF_EXCEPTION(6, "MSEN fail\n");
+ return PTR_ERR(request);
+ }
+
+ request->op = TO_MSEN;
+ tape_ccw_end(request->cpaddr, SENSE, 32, request->cpdata);
+ rc = tape_do_io_interruptible(device, request);
+ __tape_34xx_medium_sense(request);
return rc;
}
+static void tape_34xx_medium_sense_async(struct tape_device *device)
+{
+ struct tape_request *request;
+
+ request = tape_alloc_request(1, 32);
+ if (IS_ERR(request)) {
+ DBF_EXCEPTION(6, "MSEN fail\n");
+ return;
+ }
+
+ request->op = TO_MSEN;
+ tape_ccw_end(request->cpaddr, SENSE, 32, request->cpdata);
+ request->callback = (void *) __tape_34xx_medium_sense;
+ request->callback_data = NULL;
+ tape_do_io_async(device, request);
+}
+
struct tape_34xx_work {
struct tape_device *device;
enum tape_op op;
@@ -109,6 +129,9 @@
* is inserted but cannot call tape_do_io* from an interrupt context.
* Maybe that's useful for other actions we want to start from the
* interrupt handler.
+ * Note: the work handler is called by the system work queue. The tape
+ * commands started by the handler need to be asynchrounous, otherwise
+ * a deadlock can occur e.g. in case of a deferred cc=1 (see __tape_do_irq).
*/
static void
tape_34xx_work_handler(struct work_struct *work)
@@ -119,7 +142,7 @@
switch(p->op) {
case TO_MSEN:
- tape_34xx_medium_sense(device);
+ tape_34xx_medium_sense_async(device);
break;
default:
DBF_EVENT(3, "T34XX: internal error: unknown work\n");
diff --git a/drivers/s390/char/tape_3590.c b/drivers/s390/char/tape_3590.c
index fbe361f..de2e99e 100644
--- a/drivers/s390/char/tape_3590.c
+++ b/drivers/s390/char/tape_3590.c
@@ -329,17 +329,17 @@
/*
* Enable encryption
*/
-static int tape_3592_enable_crypt(struct tape_device *device)
+static struct tape_request *__tape_3592_enable_crypt(struct tape_device *device)
{
struct tape_request *request;
char *data;
DBF_EVENT(6, "tape_3592_enable_crypt\n");
if (!crypt_supported(device))
- return -ENOSYS;
+ return ERR_PTR(-ENOSYS);
request = tape_alloc_request(2, 72);
if (IS_ERR(request))
- return PTR_ERR(request);
+ return request;
data = request->cpdata;
memset(data,0,72);
@@ -354,23 +354,42 @@
request->op = TO_CRYPT_ON;
tape_ccw_cc(request->cpaddr, MODE_SET_CB, 36, data);
tape_ccw_end(request->cpaddr + 1, MODE_SET_CB, 36, data + 36);
+ return request;
+}
+
+static int tape_3592_enable_crypt(struct tape_device *device)
+{
+ struct tape_request *request;
+
+ request = __tape_3592_enable_crypt(device);
+ if (IS_ERR(request))
+ return PTR_ERR(request);
return tape_do_io_free(device, request);
}
+static void tape_3592_enable_crypt_async(struct tape_device *device)
+{
+ struct tape_request *request;
+
+ request = __tape_3592_enable_crypt(device);
+ if (!IS_ERR(request))
+ tape_do_io_async_free(device, request);
+}
+
/*
* Disable encryption
*/
-static int tape_3592_disable_crypt(struct tape_device *device)
+static struct tape_request *__tape_3592_disable_crypt(struct tape_device *device)
{
struct tape_request *request;
char *data;
DBF_EVENT(6, "tape_3592_disable_crypt\n");
if (!crypt_supported(device))
- return -ENOSYS;
+ return ERR_PTR(-ENOSYS);
request = tape_alloc_request(2, 72);
if (IS_ERR(request))
- return PTR_ERR(request);
+ return request;
data = request->cpdata;
memset(data,0,72);
@@ -383,9 +402,28 @@
tape_ccw_cc(request->cpaddr, MODE_SET_CB, 36, data);
tape_ccw_end(request->cpaddr + 1, MODE_SET_CB, 36, data + 36);
+ return request;
+}
+
+static int tape_3592_disable_crypt(struct tape_device *device)
+{
+ struct tape_request *request;
+
+ request = __tape_3592_disable_crypt(device);
+ if (IS_ERR(request))
+ return PTR_ERR(request);
return tape_do_io_free(device, request);
}
+static void tape_3592_disable_crypt_async(struct tape_device *device)
+{
+ struct tape_request *request;
+
+ request = __tape_3592_disable_crypt(device);
+ if (!IS_ERR(request))
+ tape_do_io_async_free(device, request);
+}
+
/*
* IOCTL: Set encryption status
*/
@@ -457,8 +495,7 @@
/*
* SENSE Medium: Get Sense data about medium state
*/
-static int
-tape_3590_sense_medium(struct tape_device *device)
+static int tape_3590_sense_medium(struct tape_device *device)
{
struct tape_request *request;
@@ -470,6 +507,18 @@
return tape_do_io_free(device, request);
}
+static void tape_3590_sense_medium_async(struct tape_device *device)
+{
+ struct tape_request *request;
+
+ request = tape_alloc_request(1, 128);
+ if (IS_ERR(request))
+ return;
+ request->op = TO_MSEN;
+ tape_ccw_end(request->cpaddr, MEDIUM_SENSE, 128, request->cpdata);
+ tape_do_io_async_free(device, request);
+}
+
/*
* MTTELL: Tell block. Return the number of block relative to current file.
*/
@@ -546,15 +595,14 @@
* 2. The attention msg is written to the "read subsystem data" buffer.
* In this case we probably should print it to the console.
*/
-static int
-tape_3590_read_attmsg(struct tape_device *device)
+static void tape_3590_read_attmsg_async(struct tape_device *device)
{
struct tape_request *request;
char *buf;
request = tape_alloc_request(3, 4096);
if (IS_ERR(request))
- return PTR_ERR(request);
+ return;
request->op = TO_READ_ATTMSG;
buf = request->cpdata;
buf[0] = PREP_RD_SS_DATA;
@@ -562,12 +610,15 @@
tape_ccw_cc(request->cpaddr, PERFORM_SS_FUNC, 12, buf);
tape_ccw_cc(request->cpaddr + 1, READ_SS_DATA, 4096 - 12, buf + 12);
tape_ccw_end(request->cpaddr + 2, NOP, 0, NULL);
- return tape_do_io_free(device, request);
+ tape_do_io_async_free(device, request);
}
/*
* These functions are used to schedule follow-up actions from within an
* interrupt context (like unsolicited interrupts).
+ * Note: the work handler is called by the system work queue. The tape
+ * commands started by the handler need to be asynchrounous, otherwise
+ * a deadlock can occur e.g. in case of a deferred cc=1 (see __tape_do_irq).
*/
struct work_handler_data {
struct tape_device *device;
@@ -583,16 +634,16 @@
switch (p->op) {
case TO_MSEN:
- tape_3590_sense_medium(p->device);
+ tape_3590_sense_medium_async(p->device);
break;
case TO_READ_ATTMSG:
- tape_3590_read_attmsg(p->device);
+ tape_3590_read_attmsg_async(p->device);
break;
case TO_CRYPT_ON:
- tape_3592_enable_crypt(p->device);
+ tape_3592_enable_crypt_async(p->device);
break;
case TO_CRYPT_OFF:
- tape_3592_disable_crypt(p->device);
+ tape_3592_disable_crypt_async(p->device);
break;
default:
DBF_EVENT(3, "T3590: work handler undefined for "