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scsi: ufs: core: Fix another task management completion race

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hba->outstanding_tasks, which is read under host_lock spinlock, tells the
interrupt handler what task management tags are in use by the driver.  The
doorbell register bits indicate which tags are in use by the hardware.  A
doorbell bit that is 0 is because the bit has yet to be set by the driver,
or because the task is complete. It is only possible to disambiguate the 2
cases, if reading/writing the doorbell register is synchronized with
reading/writing hba->outstanding_tasks.

For that reason, reading REG_UTP_TASK_REQ_DOOR_BELL must be done under
spinlock.

Link: https://lore.kernel.org/r/20211108064815.569494-3-adrian.hunter@intel.com
Fixes: f5ef336fd2 ("scsi: ufs: core: Fix task management completion")
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Adrian Hunter 2021-11-08 08:48:15 +02:00 committed by Martin K. Petersen
parent 886fe2915c
commit 5cb37a2635
1 changed files with 1 additions and 2 deletions
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3
drivers/scsi/ufs/ufshcd.c
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@ -6453,9 +6453,8 @@ static irqreturn_t ufshcd_tmc_handler(struct ufs_hba *hba)
irqreturn_t ret = IRQ_NONE;
int tag;
pending = ufshcd_readl(hba, REG_UTP_TASK_REQ_DOOR_BELL);
spin_lock_irqsave(hba->host->host_lock, flags);
pending = ufshcd_readl(hba, REG_UTP_TASK_REQ_DOOR_BELL);
issued = hba->outstanding_tasks & ~pending;
for_each_set_bit(tag, &issued, hba->nutmrs) {
struct request *req = hba->tmf_rqs[tag];