scmd->abort_work is only scheduled after the block layer has marked
the request associated with a command as complete and for commands
that are not on the eh_cmd_q list. A SCSI command is only requeued
after the scmd->abort_work handler has started (requeueing clears
the "complete" flag). This means that the cancel_delayed_work()
statement in scsi_put_command() is a no-op. Hence remove it.
Additionally, document how it is avoided that scsi_finish_command()
and the SCSI error handler code are invoked concurrently for the
same command via WARN_ON_ONCE() statements. This should avoid that
the scsi error handler code confuses its readers.
Signed-off-by: Bart Van Assche <bvanass...@acm.org>
Cc: Hannes Reinecke <h...@suse.de>
Cc: Paolo Bonzini <pbonz...@redhat.com>
Cc: Christoph Hellwig <h...@infradead.org>
Cc: Jens Axboe <ax...@fb.com>
Cc: Joe Lawrence <jdl1...@gmail.com>
---
block/blk-softirq.c | 6 ++++++
drivers/scsi/scsi.c | 2 --
drivers/scsi/scsi_error.c | 28 ++++++++++++++++++++++++++++
include/linux/blkdev.h | 1 +
4 files changed, 35 insertions(+), 2 deletions(-)
diff --git a/block/blk-softirq.c b/block/blk-softirq.c
index 53b1737..59bb52d 100644
--- a/block/blk-softirq.c
+++ b/block/blk-softirq.c
@@ -172,6 +172,12 @@ void blk_complete_request(struct request *req)
}
EXPORT_SYMBOL(blk_complete_request);
+bool blk_rq_completed(struct request *rq)
+{
+ return test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
+}
+EXPORT_SYMBOL(blk_rq_completed);
+
static __init int blk_softirq_init(void)
{
int i;
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index 88d46fe..04a282a 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -334,8 +334,6 @@ void scsi_put_command(struct scsi_cmnd *cmd)
list_del_init(&cmd->list);
spin_unlock_irqrestore(&cmd->device->list_lock, flags);
- cancel_delayed_work(&cmd->abort_work);
-
__scsi_put_command(cmd->device->host, cmd);
}
EXPORT_SYMBOL(scsi_put_command);
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 14ce3b4..32a8cd1 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -108,6 +108,28 @@ static int scsi_host_eh_past_deadline(struct Scsi_Host
*shost)
return 1;
}
+static bool scmd_being_handled_in_other_context(struct scsi_cmnd *scmd)
+{
+ struct Scsi_Host *shost = scmd->device->host;
+ struct scsi_cmnd *c;
+ unsigned long flags;
+ bool ret = false;
+
+ if (!blk_rq_completed(scmd->request))
+ return true;
+
+ spin_lock_irqsave(shost->host_lock, flags);
+ list_for_each_entry(c, &shost->eh_cmd_q, eh_entry) {
+ if (c == scmd) {
+ ret = true;
+ break;
+ }
+ }
+ spin_unlock_irqrestore(shost->host_lock, flags);
+
+ return ret;
+}
+
/**
* scmd_eh_abort_handler - Handle command aborts
* @work: command to be aborted.
@@ -120,6 +142,8 @@ scmd_eh_abort_handler(struct work_struct *work)
struct scsi_device *sdev = scmd->device;
int rtn;
+ WARN_ON_ONCE(scmd_being_handled_in_other_context(scmd));
+
if (scsi_host_eh_past_deadline(sdev->host)) {
SCSI_LOG_ERROR_RECOVERY(3,
scmd_printk(KERN_INFO, scmd,
@@ -185,6 +209,8 @@ scsi_abort_command(struct scsi_cmnd *scmd)
struct Scsi_Host *shost = sdev->host;
unsigned long flags;
+ WARN_ON_ONCE(scmd_being_handled_in_other_context(scmd));
+
if (scmd->eh_eflags & SCSI_EH_ABORT_SCHEDULED) {
/*
* Retry after abort failed, escalate to next level.
@@ -237,6 +263,8 @@ int scsi_eh_scmd_add(struct scsi_cmnd *scmd, int eh_flag)
unsigned long flags;
int ret = 0;
+ WARN_ON_ONCE(scmd_being_handled_in_other_context(scmd));
+
if (!shost->ehandler)
return 0;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 0d84981..a621bc5 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -952,6 +952,7 @@ extern void blk_complete_request(struct request *);
extern void __blk_complete_request(struct request *);
extern void blk_abort_request(struct request *);
extern void blk_unprep_request(struct request *);
+extern bool blk_rq_completed(struct request *);
/*
* Access functions for manipulating queue properties
--
1.8.4.5
--
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