On Fri, Feb 10, 2017 at 03:56:04PM -0800, Bart Van Assche wrote:
> After srp_process_rsp() returns there is a short time during which
> the scsi_host_find_tag() call will return a pointer to the SCSI
> command that is being completed. If during that time a duplicate
> response is received, avoid that the following call stack appears:
>
> BUG: unable to handle kernel NULL pointer dereference at (null)
> IP: srp_recv_done+0x450/0x6b0 [ib_srp]
> Oops: 0000 [#1] SMP
> CPU: 10 PID: 0 Comm: swapper/10 Not tainted 4.10.0-rc7-dbg+ #1
> Call Trace:
> <IRQ>
> __ib_process_cq+0x4b/0xd0 [ib_core]
> ib_poll_handler+0x1d/0x70 [ib_core]
> irq_poll_softirq+0xba/0x120
> __do_softirq+0xba/0x4c0
> irq_exit+0xbe/0xd0
> smp_apic_timer_interrupt+0x38/0x50
> apic_timer_interrupt+0x90/0xa0
> </IRQ>
> cpuidle_enter_state+0xf2/0x370
> cpuidle_enter+0x12/0x20
> call_cpuidle+0x1e/0x40
> do_idle+0xe3/0x1c0
> cpu_startup_entry+0x18/0x20
> start_secondary+0x103/0x130
> start_cpu+0x14/0x14
> RIP: srp_recv_done+0x450/0x6b0 [ib_srp] RSP: ffff88046f483e20
>
> Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxxxxxx>
> Cc: Israel Rukshin <israelr@xxxxxxxxxxxx>
> Cc: Max Gurtovoy <maxg@xxxxxxxxxxxx>
> Cc: Laurence Oberman <loberman@xxxxxxxxxx>
> Cc: Steve Feeley <Steve.Feeley@xxxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> ---
> drivers/infiniband/ulp/srp/ib_srp.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
> index 79bf48477ddb..4068d34f5427 100644
> --- a/drivers/infiniband/ulp/srp/ib_srp.c
> +++ b/drivers/infiniband/ulp/srp/ib_srp.c
> @@ -1899,7 +1899,14 @@ static void srp_process_rsp(struct srp_rdma_ch *ch, struct srp_rsp *rsp)
> scmnd = scsi_host_find_tag(target->scsi_host, rsp->tag);
> if (scmnd) {
> req = (void *)scmnd->host_scribble;
> - scmnd = srp_claim_req(ch, req, NULL, scmnd);
> + if (req) {
> + scmnd = srp_claim_req(ch, req, NULL, scmnd);
> + } else {
> + shost_printk(KERN_ERR, target->scsi_host,
> + "NULL host_scribble for response with tag %#llx\n",
> + rsp->tag);
> + scmnd = NULL;
> + }
> }
> if (!scmnd) {
> shost_printk(KERN_ERR, target->scsi_host,
You have the chance to print the message below together with your new
print, because scmd will be NULL.
What about to do the following check "if (scmd && scmd->host_scribble)"
instead of your proposed patch?
Thanks
> --
> 2.11.0
>
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