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Subject[PATCH RT 22/27] sas-ata/isci: dontt disable interrupts in qc_issue handler
3.4.106-rt132-rc1 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Paul Gortmaker <paul.gortmaker@windriver.com>

On 3.14-rt we see the following trace on Canoe Pass for
SCSI_ISCI "Intel(R) C600 Series Chipset SAS Controller"
when the sas qc_issue handler is run:

BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:905
in_atomic(): 0, irqs_disabled(): 1, pid: 432, name: udevd
CPU: 11 PID: 432 Comm: udevd Not tainted 3.14.28-rt22 #2
Hardware name: Intel Corporation S2600CP/S2600CP, BIOS SE5C600.86B.02.01.0002.082220131453 08/22/2013
ffff880fab500000 ffff880fa9f239c0 ffffffff81a2d273 0000000000000000
ffff880fa9f239d8 ffffffff8107f023 ffff880faac23dc0 ffff880fa9f239f0
ffffffff81a33cc0 ffff880faaeb1400 ffff880fa9f23a40 ffffffff815de891
Call Trace:
[<ffffffff81a2d273>] dump_stack+0x4e/0x7a
[<ffffffff8107f023>] __might_sleep+0xe3/0x160
[<ffffffff81a33cc0>] rt_spin_lock+0x20/0x50
[<ffffffff815de891>] isci_task_execute_task+0x171/0x2f0 <-----
[<ffffffff815cfecb>] sas_ata_qc_issue+0x25b/0x2a0
[<ffffffff81606363>] ata_qc_issue+0x1f3/0x370
[<ffffffff8160c600>] ? ata_scsi_invalid_field+0x40/0x40
[<ffffffff8160c8f5>] ata_scsi_translate+0xa5/0x1b0
[<ffffffff8160efc6>] ata_sas_queuecmd+0x86/0x280
[<ffffffff815ce446>] sas_queuecommand+0x196/0x230
[<ffffffff81081fad>] ? get_parent_ip+0xd/0x50
[<ffffffff815b05a4>] scsi_dispatch_cmd+0xb4/0x210
[<ffffffff815b7744>] scsi_request_fn+0x314/0x530

and gdb shows:

(gdb) list * isci_task_execute_task+0x171
0xffffffff815ddfb1 is in isci_task_execute_task (drivers/scsi/isci/task.c:138).
133 dev_dbg(&ihost->pdev->dev, "%s: num=%d\n", __func__, num);
134
135 for_each_sas_task(num, task) {
136 enum sci_status status = SCI_FAILURE;
137
138 spin_lock_irqsave(&ihost->scic_lock, flags); <-----
139 idev = isci_lookup_device(task->dev);
140 io_ready = isci_device_io_ready(idev, task);
141 tag = isci_alloc_tag(ihost);
142 spin_unlock_irqrestore(&ihost->scic_lock, flags);
(gdb)

In addition to the scic_lock, the function also contains locking of
the task_state_lock -- which is clearly not a candidate for raw lock
conversion. As can be seen by the comment nearby, we really should
be running the qc_issue code with interrupts enabled anyway.

Cc: stable-rt@vger.kernel.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
drivers/scsi/libsas/sas_ata.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
index 51ee663c1310..38c9f30d1064 100644
--- a/drivers/scsi/libsas/sas_ata.c
+++ b/drivers/scsi/libsas/sas_ata.c
@@ -191,7 +191,7 @@ static unsigned int sas_ata_qc_issue(struct ata_queued_cmd *qc)
/* TODO: audit callers to ensure they are ready for qc_issue to
* unconditionally re-enable interrupts
*/
- local_irq_save(flags);
+ local_irq_save_nort(flags);
spin_unlock(ap->lock);

/* If the device fell off, no sense in issuing commands */
@@ -261,7 +261,7 @@ static unsigned int sas_ata_qc_issue(struct ata_queued_cmd *qc)

out:
spin_lock(ap->lock);
- local_irq_restore(flags);
+ local_irq_restore_nort(flags);
return ret;
}

--
2.1.4



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