[PATCH AUTOSEL 4.19 14/37] scsi: RDMA/srp: Fix a sleep-in-invalid-context bug

Sasha Levin
2019-10-25T14:04:46Z

From: Bart Van Assche <bvanassche@acm.org>

[ Upstream commit fd56141244066a6a21ef458670071c58b6402035 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/infiniband/ulp/srp/ib_srp.c | 21 ++-------------------
1 file changed, 2 insertions(+), 19 deletions(-)

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index bc6a44a16445c..f619fd7d8f9e6 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -2279,7 +2279,6 @@ 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;
@@ -2289,16 +2288,6 @@ 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))
@@ -2360,13 +2349,7 @@ 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);
@@ -2388,7 +2371,7 @@ static int srp_queuecommand(struct Scsi_Host *shost, struct scsi_cmnd *scmnd)
ret = SCSI_MLQUEUE_HOST_BUSY;
}

- goto unlock_rport;
+ return ret;
}

/*
--
2.20.1