[PATCH] libata: implement ata_exec_internal()
This patch implements ata_exec_internal() function which performs
libata internal command execution. Previously, this was done by each
user by manually initializing a qc, issueing it, waiting for its
completion and handling errors. In addition to obvious code
factoring, using ata_exec_internal() fixes the following bugs.
* qc not freed on issue failure
* ap->qactive clearing could race with the next internal command
* race between timeout handling and irq
* ignoring error condition not represented in tf->status
Also, qc & hardware are not accessed anymore once it's completed,
making internal commands more conformant with general semantics.
ata_exec_internal() also makes it easy to issue internal commands from
multiple threads if that becomes necessary.
This patch only implements ata_exec_internal(). A following patch
will convert all users.
Signed-off-by: Tejun Heo <htejun@gmail.com>
--
Jeff, all patches have been regenerated against upstream branch as of
today. (575ab52a218e4ff0667a6cbd972c3af443ee8713)
Also, I took out a debug printk from ata_exec_internal (don't know how
that one got left there). Other than that, all patches are identical
to the previous posting.
Thanks. :-)
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index a0060cf..de80abe 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -1046,6 +1046,105 @@
return modes;
}
+struct ata_exec_internal_arg {
+ unsigned int err_mask;
+ struct ata_taskfile *tf;
+ struct completion *waiting;
+};
+
+int ata_qc_complete_internal(struct ata_queued_cmd *qc)
+{
+ struct ata_exec_internal_arg *arg = qc->private_data;
+ struct completion *waiting = arg->waiting;
+
+ if (!(qc->err_mask & ~AC_ERR_DEV))
+ qc->ap->ops->tf_read(qc->ap, arg->tf);
+ arg->err_mask = qc->err_mask;
+ arg->waiting = NULL;
+ complete(waiting);
+
+ return 0;
+}
+
+/**
+ * ata_exec_internal - execute libata internal command
+ * @ap: Port to which the command is sent
+ * @dev: Device to which the command is sent
+ * @tf: Taskfile registers for the command and the result
+ * @dma_dir: Data tranfer direction of the command
+ * @buf: Data buffer of the command
+ * @buflen: Length of data buffer
+ *
+ * Executes libata internal command with timeout. @tf contains
+ * command on entry and result on return. Timeout and error
+ * conditions are reported via return value. No recovery action
+ * is taken after a command times out. It's caller's duty to
+ * clean up after timeout.
+ *
+ * LOCKING:
+ * None. Should be called with kernel context, might sleep.
+ */
+
+static unsigned
+ata_exec_internal(struct ata_port *ap, struct ata_device *dev,
+ struct ata_taskfile *tf,
+ int dma_dir, void *buf, unsigned int buflen)
+{
+ u8 command = tf->command;
+ struct ata_queued_cmd *qc;
+ DECLARE_COMPLETION(wait);
+ unsigned long flags;
+ struct ata_exec_internal_arg arg;
+
+ spin_lock_irqsave(&ap->host_set->lock, flags);
+
+ qc = ata_qc_new_init(ap, dev);
+ BUG_ON(qc == NULL);
+
+ qc->tf = *tf;
+ qc->dma_dir = dma_dir;
+ if (dma_dir != DMA_NONE) {
+ ata_sg_init_one(qc, buf, buflen);
+ qc->nsect = buflen / ATA_SECT_SIZE;
+ }
+
+ arg.waiting = &wait;
+ arg.tf = tf;
+ qc->private_data = &arg;
+ qc->complete_fn = ata_qc_complete_internal;
+
+ if (ata_qc_issue(qc))
+ goto issue_fail;
+
+ spin_unlock_irqrestore(&ap->host_set->lock, flags);
+
+ if (!wait_for_completion_timeout(&wait, ATA_TMOUT_INTERNAL)) {
+ spin_lock_irqsave(&ap->host_set->lock, flags);
+
+ /* We're racing with irq here. If we lose, the
+ * following test prevents us from completing the qc
+ * again. If completion irq occurs after here but
+ * before the caller cleans up, it will result in a
+ * spurious interrupt. We can live with that.
+ */
+ if (arg.waiting) {
+ qc->err_mask = AC_ERR_OTHER;
+ ata_qc_complete(qc);
+ printk(KERN_WARNING "ata%u: qc timeout (cmd 0x%x)\n",
+ ap->id, command);
+ }
+
+ spin_unlock_irqrestore(&ap->host_set->lock, flags);
+ }
+
+ return arg.err_mask;
+
+ issue_fail:
+ ata_qc_free(qc);
+ spin_unlock_irqrestore(&ap->host_set->lock, flags);
+ return AC_ERR_OTHER;
+}
+
static int ata_qc_wait_err(struct ata_queued_cmd *qc,
struct completion *wait)
{