From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sagi Grimberg Subject: Re: [PATCH] IB/srp: Process REQ_PREEMPT requests correctly Date: Thu, 29 Jan 2015 15:44:32 +0200 Message-ID: <54CA3940.7040205@dev.mellanox.co.il> References: <54CA2F48.605@sandisk.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <54CA2F48.605-XdAiOPVOjttBDgjK7y7TUQ@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Bart Van Assche , Roland Dreier Cc: Max Gurtuvoy , Sagi Grimberg , linux-rdma , "linux-scsi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-rdma@vger.kernel.org On 1/29/2015 3:02 PM, Bart Van Assche wrote: > Delay REQ_PREEMPT requests submitted against a blocked device > until the device is unblocked by returning SCSI_MLQUEUE_HOST_BUSY > to the SCSI mid-layer. This avoids that a rescan shortly after a > cable pull sporadically triggers the following kernel oops: > > BUG: unable to handle kernel paging request at ffffc9001a6bc084 > IP: [] mlx4_ib_post_send+0xd2/0xb30 [mlx4_ib] > Process rescan-scsi-bus (pid: 9241, threadinfo ffff88053484a000, task ffff880534aae100) > Call Trace: > [] srp_post_send+0x65/0x70 [ib_srp] > [] srp_queuecommand+0x1cf/0x3e0 [ib_srp] > [] scsi_dispatch_cmd+0x101/0x280 [scsi_mod] > [] scsi_request_fn+0x411/0x4d0 [scsi_mod] > [] __blk_run_queue+0x27/0x30 > [] blk_execute_rq_nowait+0x82/0x110 > [] blk_execute_rq+0x62/0xf0 > [] scsi_execute+0xe8/0x190 [scsi_mod] > [] scsi_execute_req+0xa3/0x130 [scsi_mod] > [] scsi_probe_lun+0x17a/0x450 [scsi_mod] > [] scsi_probe_and_add_lun+0x156/0x480 [scsi_mod] > [] __scsi_scan_target+0xdf/0x1f0 [scsi_mod] > [] scsi_scan_host_selected+0x183/0x1c0 [scsi_mod] > [] scsi_scan+0xdb/0xe0 [scsi_mod] > [] store_scan+0x13/0x20 [scsi_mod] > [] sysfs_write_file+0xcb/0x160 > [] vfs_write+0xce/0x140 > [] sys_write+0x53/0xa0 > [] system_call_fastpath+0x16/0x1b > [<00007f611c9d9300>] 0x7f611c9d92ff > > Reported-by: Max Gurtuvoy > Signed-off-by: Bart Van Assche > Cc: Sagi Grimberg > Cc: > --- > drivers/infiniband/ulp/srp/ib_srp.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c > index 0747c05..77a7a2f 100644 > --- a/drivers/infiniband/ulp/srp/ib_srp.c > +++ b/drivers/infiniband/ulp/srp/ib_srp.c > @@ -2003,8 +2003,13 @@ static int srp_queuecommand(struct Scsi_Host *shost, struct scsi_cmnd *scmnd) > if (in_scsi_eh) > mutex_lock(&rport->mutex); > > + /* > + * The "blocked" state of SCSI devices is ignored by the SCSI core for > + * REQ_PREEMPT requests. Hence the explicit check below for the SCSI > + * device state. > + */ > scmnd->result = srp_chkready(target->rport); > - if (unlikely(scmnd->result)) > + if (unlikely(scmnd->result != 0 || scsi_device_blocked(scmnd->device))) > goto err; > > WARN_ON_ONCE(scmnd->request->tag < 0); > Yep... Reviewed-by: Sagi Grimberg -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html