Commit fd561412 authored Jun 17, 2019 by Bart Van Assche Committed by Martin K. Petersen Jun 20, 2019

scsi: RDMA/srp: Fix a sleep-in-invalid-context bug



The previous patch guarantees that srp_queuecommand() does not get
invoked while reconnecting occurs. Hence remove the code from
srp_queuecommand() that prevents command queueing while reconnecting.
This patch avoids that the following can appear in the kernel log:

BUG: sleeping function called from invalid context at kernel/locking/mutex.c:747
in_atomic(): 1, irqs_disabled(): 0, pid: 5600, name: scsi_eh_9
1 lock held by scsi_eh_9/5600:
 #0:  (rcu_read_lock){....}, at: [<00000000cbb798c7>] __blk_mq_run_hw_queue+0xf1/0x1e0
Preemption disabled at:
[<00000000139badf2>] __blk_mq_delay_run_hw_queue+0x78/0xf0
CPU: 9 PID: 5600 Comm: scsi_eh_9 Tainted: G        W        4.15.0-rc4-dbg+ #1
Hardware name: Dell Inc. PowerEdge R720/0VWT90, BIOS 2.5.4 01/22/2016
Call Trace:
 dump_stack+0x67/0x99
 ___might_sleep+0x16a/0x250 [ib_srp]
 __mutex_lock+0x46/0x9d0
 srp_queuecommand+0x356/0x420 [ib_srp]
 scsi_dispatch_cmd+0xf6/0x3f0
 scsi_queue_rq+0x4a8/0x5f0
 blk_mq_dispatch_rq_list+0x73/0x440
 blk_mq_sched_dispatch_requests+0x109/0x1a0
 __blk_mq_run_hw_queue+0x131/0x1e0
 __blk_mq_delay_run_hw_queue+0x9a/0xf0
 blk_mq_run_hw_queue+0xc0/0x1e0
 blk_mq_start_hw_queues+0x2c/0x40
 scsi_run_queue+0x18e/0x2d0
 scsi_run_host_queues+0x22/0x40
 scsi_error_handler+0x18d/0x5f0
 kthread+0x11c/0x140
 ret_from_fork+0x24/0x30

Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Laurence Oberman <loberman@redhat.com>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Leon Romanovsky <leonro@mellanox.com>
Cc: Doug Ledford <dledford@redhat.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

parent bbe9fb0d

drivers/infiniband/ulp/srp/ib_srp.c

+2 −19

Original line number	Diff line number	Diff line
		@@ -2338,7 +2338,6 @@ static void srp_handle_qp_err(struct ib_cq cq, struct ib_wc wc,
		static int srp_queuecommand(struct Scsi_Host shost, struct scsi_cmnd scmnd)
		{
		struct srp_target_port *target = host_to_target(shost);
		struct srp_rport *rport = target->rport;
		struct srp_rdma_ch *ch;
		struct srp_request *req;
		struct srp_iu *iu;
		@@ -2348,16 +2347,6 @@ static int srp_queuecommand(struct Scsi_Host shost, struct scsi_cmnd scmnd)
		u32 tag;
		u16 idx;
		int len, ret;
		const bool in_scsi_eh = !in_interrupt() && current == shost->ehandler;

		/*
		* The SCSI EH thread is the only context from which srp_queuecommand()
		* can get invoked for blocked devices (SDEV_BLOCK /
		* SDEV_CREATED_BLOCK). Avoid racing with srp_reconnect_rport() by
		* locking the rport mutex if invoked from inside the SCSI EH.
		*/
		if (in_scsi_eh)
		mutex_lock(&rport->mutex);

		scmnd->result = srp_chkready(target->rport);
		if (unlikely(scmnd->result))
		@@ -2426,13 +2415,7 @@ static int srp_queuecommand(struct Scsi_Host shost, struct scsi_cmnd scmnd)
		goto err_unmap;
		}

		ret = 0;

		unlock_rport:
		if (in_scsi_eh)
		mutex_unlock(&rport->mutex);

		return ret;
		return 0;

		err_unmap:
		srp_unmap_data(scmnd, ch, req);
		@@ -2454,7 +2437,7 @@ err:
		ret = SCSI_MLQUEUE_HOST_BUSY;
		}

		goto unlock_rport;
		return ret;
		}

		/*

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