2011-04-18 18:54:29

by Alexey Khoroshilov

Subject: [PATCH] [SCSI] mpt2sas: fix double mutex lock in NON_BLOCKING state

If mutex_trylock succeed, the control flow goes to mutex_lock_interruptible()
that is not a good thing.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <[email protected]>
---
drivers/scsi/mpt2sas/mpt2sas_ctl.c | 24 ++++++++++++++++--------
1 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/drivers/scsi/mpt2sas/mpt2sas_ctl.c b/drivers/scsi/mpt2sas/mpt2sas_ctl.c
index 1c6d2b4..9bd7ffc 100644
--- a/drivers/scsi/mpt2sas/mpt2sas_ctl.c
+++ b/drivers/scsi/mpt2sas/mpt2sas_ctl.c
@@ -648,8 +648,10 @@ _ctl_do_mpt_command(struct MPT2SAS_ADAPTER *ioc,

issue_reset = 0;

- if (state == NON_BLOCKING && !mutex_trylock(&ioc->ctl_cmds.mutex))
- return -EAGAIN;
+ if (state == NON_BLOCKING) {
+ if (!mutex_trylock(&ioc->ctl_cmds.mutex))
+ return -EAGAIN;
+ }
else if (mutex_lock_interruptible(&ioc->ctl_cmds.mutex))
return -ERESTARTSYS;

@@ -1587,8 +1589,10 @@ _ctl_diag_register(void __user *arg, enum block_state state)
if (_ctl_verify_adapter(karg.hdr.ioc_number, &ioc) == -1 || !ioc)
return -ENODEV;

- if (state == NON_BLOCKING && !mutex_trylock(&ioc->ctl_cmds.mutex))
- return -EAGAIN;
+ if (state == NON_BLOCKING) {
+ if (!mutex_trylock(&ioc->ctl_cmds.mutex))
+ return -EAGAIN;
+ }
else if (mutex_lock_interruptible(&ioc->ctl_cmds.mutex))
return -ERESTARTSYS;
rc = _ctl_diag_register_2(ioc, &karg);
@@ -1932,8 +1936,10 @@ _ctl_diag_release(void __user *arg, enum block_state state)
return 0;
}

- if (state == NON_BLOCKING && !mutex_trylock(&ioc->ctl_cmds.mutex))
- return -EAGAIN;
+ if (state == NON_BLOCKING) {
+ if (!mutex_trylock(&ioc->ctl_cmds.mutex))
+ return -EAGAIN;
+ }
else if (mutex_lock_interruptible(&ioc->ctl_cmds.mutex))
return -ERESTARTSYS;

@@ -2033,8 +2039,10 @@ _ctl_diag_read_buffer(void __user *arg, enum block_state state)
}
/* Get a free request frame and save the message context.
*/
- if (state == NON_BLOCKING && !mutex_trylock(&ioc->ctl_cmds.mutex))
- return -EAGAIN;
+ if (state == NON_BLOCKING) {
+ if (!mutex_trylock(&ioc->ctl_cmds.mutex))
+ return -EAGAIN;
+ }
else if (mutex_lock_interruptible(&ioc->ctl_cmds.mutex))
return -ERESTARTSYS;

--
1.7.1