From: Bart Van Assche <bvanassche-HInyCGIudOg@public.gmane.org>
To: dongsu.park-EIkl63zCoXaH+58JC4qpiA@public.gmane.org
Cc: dillowda-1Heg1YXhbW8@public.gmane.org,
roland-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
sean.hefty-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org,
hal.rosenstock-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org,
JBottomley-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org,
linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Sebastian Riemer
<sebastian.riemer-EIkl63zCoXaH+58JC4qpiA@public.gmane.org>
Subject: Re: [PATCH 2/5] ib_srp: removed superfluous warning in send timeout case
Date: Sat, 01 Sep 2012 07:44:02 +0000 [thread overview]
Message-ID: <5041BCC2.8010309@acm.org> (raw)
In-Reply-To: <1346443241-24844-3-git-send-email-dongsu.park-EIkl63zCoXaH+58JC4qpiA@public.gmane.org>
On 08/31/12 20:00, dongsu.park-EIkl63zCoXaH+58JC4qpiA@public.gmane.org wrote:
> From: Dongsu Park <dongsu.park-EIkl63zCoXaH+58JC4qpiA@public.gmane.org>
>
> Signed-off-By: Sebastian Riemer <sebastian.riemer-EIkl63zCoXaH+58JC4qpiA@public.gmane.org>
> ---
> drivers/infiniband/ulp/srp/ib_srp.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
> index a0d0ca2..1b274484 100644
> --- a/drivers/infiniband/ulp/srp/ib_srp.c
> +++ b/drivers/infiniband/ulp/srp/ib_srp.c
> @@ -534,7 +534,6 @@ static void srp_wait_last_send_wqe(struct srp_target_port *target)
> msleep(20);
> }
>
> - WARN_ON(!target->last_send_wqe);
> }
>
> static void srp_disconnect_target(struct srp_target_port *target)
The purpose of the functions srp_wait_last_recv_wqe() and
srp_wait_last_send_wqe() is to wait until the IB HCA has finished
delivering work completions to ib_srp. The InfiniBand Architecture
Manual specifies how long that can take. If the above WARN_ON()
statement is hit it means that it took longer than expected before all
pending work was completed. Letting srp_wait_last_send_wqe() return
before all pending work has been completed is dangerous because that may
trigger a use-after-free in the code that calls that function. So we
have to dig deeper here and find out why that WARN_ON() statement was hit.
Bart.
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next prev parent reply other threads:[~2012-09-01 7:44 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-31 20:00 [PATCH 0/5] Fix bugs in ib_srp patches for H.A. purposes dongsu.park-EIkl63zCoXaH+58JC4qpiA
2012-08-31 20:00 ` [PATCH 1/5] ib_srp: free memory correctly in srp_free_iu() dongsu.park
[not found] ` <1346443241-24844-2-git-send-email-dongsu.park-EIkl63zCoXaH+58JC4qpiA@public.gmane.org>
2012-09-01 7:32 ` Bart Van Assche
2012-08-31 20:00 ` [PATCH 2/5] ib_srp: removed superfluous warning in send timeout case dongsu.park
[not found] ` <1346443241-24844-3-git-send-email-dongsu.park-EIkl63zCoXaH+58JC4qpiA@public.gmane.org>
2012-09-01 7:44 ` Bart Van Assche [this message]
2012-08-31 20:00 ` [PATCH 3/5] ib_srp: hold a mutex when adding a new target port dongsu.park
[not found] ` <1346443241-24844-4-git-send-email-dongsu.park-EIkl63zCoXaH+58JC4qpiA@public.gmane.org>
2012-09-01 7:55 ` Bart Van Assche
2012-08-31 20:00 ` [PATCH 4/5] ib_srp: check if rport->lld_data is NULL before removing rport dongsu.park
[not found] ` <1346443241-24844-5-git-send-email-dongsu.park-EIkl63zCoXaH+58JC4qpiA@public.gmane.org>
2012-09-01 7:59 ` Bart Van Assche
[not found] ` <1346443241-24844-1-git-send-email-dongsu.park-EIkl63zCoXaH+58JC4qpiA@public.gmane.org>
2012-08-31 20:00 ` [PATCH 5/5] ib_srp: fix an error accessing invalid memory in rport_dev_loss_timedout dongsu.park-EIkl63zCoXaH+58JC4qpiA
2012-09-01 8:09 ` [PATCH 0/5] Fix bugs in ib_srp patches for H.A. purposes Bart Van Assche
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