* [PATCH v2] nvmet: Don't queue fatal error work if csts.cfs is set
@ 2016-11-06 17:26 Sagi Grimberg
2016-11-07 18:41 ` J Freyensee
0 siblings, 1 reply; 3+ messages in thread
From: Sagi Grimberg @ 2016-11-06 17:26 UTC (permalink / raw)
In the transport, in case of an interal queue error like
error completion in rdma we trigger a fatal error. However,
multiple queues in the same controller can serr error completions
and we don't want to trigger fatal error work more than once.
Reviewed-by: Christoph Hellwig <hch at lst.de>
Signed-off-by: Sagi Grimberg <sagi at grimberg.me>
---
Changes from v1:
- reversed the if condition to avoid a goto statement
Changes from v0:
- protect with ctrl lock instead of abusing atomic bitops on
ctrl->csts
drivers/nvme/target/core.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 7c0fe31ee654..55ce769cecee 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -840,9 +840,13 @@ static void nvmet_fatal_error_handler(struct work_struct *work)
void nvmet_ctrl_fatal_error(struct nvmet_ctrl *ctrl)
{
- ctrl->csts |= NVME_CSTS_CFS;
- INIT_WORK(&ctrl->fatal_err_work, nvmet_fatal_error_handler);
- schedule_work(&ctrl->fatal_err_work);
+ mutex_lock(&ctrl->lock);
+ if (!(ctrl->csts & NVME_CSTS_CFS)) {
+ ctrl->csts |= NVME_CSTS_CFS;
+ INIT_WORK(&ctrl->fatal_err_work, nvmet_fatal_error_handler);
+ schedule_work(&ctrl->fatal_err_work);
+ }
+ mutex_unlock(&ctrl->lock);
}
EXPORT_SYMBOL_GPL(nvmet_ctrl_fatal_error);
--
2.7.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH v2] nvmet: Don't queue fatal error work if csts.cfs is set
2016-11-06 17:26 [PATCH v2] nvmet: Don't queue fatal error work if csts.cfs is set Sagi Grimberg
@ 2016-11-07 18:41 ` J Freyensee
2016-11-08 10:26 ` Sagi Grimberg
0 siblings, 1 reply; 3+ messages in thread
From: J Freyensee @ 2016-11-07 18:41 UTC (permalink / raw)
On Sun, 2016-11-06@19:26 +0200, Sagi Grimberg wrote:
> In the transport, in case of an interal queue error like
> error completion in rdma we trigger a fatal error. However,
> multiple queues in the same controller can serr error completions
> and we don't want to trigger fatal error work more than once.
>
> Reviewed-by: Christoph Hellwig <hch at lst.de>
> Signed-off-by: Sagi Grimberg <sagi at grimberg.me>
> ---
> Changes from v1:
> - reversed the if condition to avoid a goto statement
>
> Changes from v0:
> - protect with ctrl lock instead of abusing atomic bitops on
> ????ctrl->csts
>
> ?drivers/nvme/target/core.c | 10 +++++++---
> ?1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
> index 7c0fe31ee654..55ce769cecee 100644
> --- a/drivers/nvme/target/core.c
> +++ b/drivers/nvme/target/core.c
> @@ -840,9 +840,13 @@ static void nvmet_fatal_error_handler(struct
> work_struct *work)
> ?
> ?void nvmet_ctrl_fatal_error(struct nvmet_ctrl *ctrl)
> ?{
> - ctrl->csts |= NVME_CSTS_CFS;
> - INIT_WORK(&ctrl->fatal_err_work, nvmet_fatal_error_handler);
> - schedule_work(&ctrl->fatal_err_work);
> + mutex_lock(&ctrl->lock);
> + if (!(ctrl->csts & NVME_CSTS_CFS)) {
> + ctrl->csts |= NVME_CSTS_CFS;
> + INIT_WORK(&ctrl->fatal_err_work,
> nvmet_fatal_error_handler);
> + schedule_work(&ctrl->fatal_err_work);
> + }
> + mutex_unlock(&ctrl->lock);
Surrounding the mutex_lock()/unlock() around the if() is definitely
safer and a more conservative, but I would think it would be OK to
stick the mutex_lock/unlock() within the if() statement (mutex_lock()
as the first line after the if() check, mutex_unlock() as the last line
of the if()), as trying to acquire a lock before checking the condition
to see if CFS needs to be set is sub-optimal.
> ?}
> ?EXPORT_SYMBOL_GPL(nvmet_ctrl_fatal_error);
> ?
^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCH v2] nvmet: Don't queue fatal error work if csts.cfs is set
2016-11-07 18:41 ` J Freyensee
@ 2016-11-08 10:26 ` Sagi Grimberg
0 siblings, 0 replies; 3+ messages in thread
From: Sagi Grimberg @ 2016-11-08 10:26 UTC (permalink / raw)
>> void nvmet_ctrl_fatal_error(struct nvmet_ctrl *ctrl)
>> {
>> - ctrl->csts |= NVME_CSTS_CFS;
>> - INIT_WORK(&ctrl->fatal_err_work, nvmet_fatal_error_handler);
>> - schedule_work(&ctrl->fatal_err_work);
>> + mutex_lock(&ctrl->lock);
>> + if (!(ctrl->csts & NVME_CSTS_CFS)) {
>> + ctrl->csts |= NVME_CSTS_CFS;
>> + INIT_WORK(&ctrl->fatal_err_work,
>> nvmet_fatal_error_handler);
>> + schedule_work(&ctrl->fatal_err_work);
>> + }
>> + mutex_unlock(&ctrl->lock);
>
> Surrounding the mutex_lock()/unlock() around the if() is definitely
> safer and a more conservative, but I would think it would be OK to
> stick the mutex_lock/unlock() within the if() statement (mutex_lock()
> as the first line after the if() check, mutex_unlock() as the last line
> of the if()), as trying to acquire a lock before checking the condition
> to see if CFS needs to be set is sub-optimal.
I don't think this is worth optimizing, it is error flow after all..
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2016-11-08 10:26 UTC | newest]
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2016-11-06 17:26 [PATCH v2] nvmet: Don't queue fatal error work if csts.cfs is set Sagi Grimberg
2016-11-07 18:41 ` J Freyensee
2016-11-08 10:26 ` Sagi Grimberg
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