From: Iago Abal <[email protected]>
The EBA code analyzer (https://github.com/models-team/eba) reported
the following double lock:
1. In function `megaraid_reset_handler' at 2571;
2. take `&adapter->pend_list_lock' for the first time at 2602:
// FIRST
spin_lock_irqsave(PENDING_LIST_LOCK(adapter), flags);
3. enter the `list_for_each_entry_safe' loop at 2603;
4. call `megaraid_mbox_mm_done' at 2616;
5. call `megaraid_mbox_runpendq' at 3782;
6. take `&adapter->pend_list_lock' for the second time at 1892:
// SECOND: DOUBLE LOCK !!!
spin_lock_irqsave(PENDING_LIST_LOCK(adapter), flags);
>From my shallow understanding of the code (so please review carefully), I think
that it is not necessary to hold `PENDING_LIST_LOCK(adapter)' while executing
the body of the `list_for_each_entry_safe' loop. I assume this because both
`megaraid_mbox_mm_done' and `megaraid_dealloc_scb' are called from several
places where, as far as I can tell, this lock is not hold. In fact, as reported
by EBA, at some point `megaraid_mbox_mm_done' will acquire this lock again.
Fixes: c005fb4fb2d2 ("[SCSI] megaraid_{mm,mbox}: fix a bug in reset handler")
Signed-off-by: Iago Abal <[email protected]>
---
drivers/scsi/megaraid/megaraid_mbox.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/scsi/megaraid/megaraid_mbox.c
b/drivers/scsi/megaraid/megaraid_mbox.c
index f0987f2..7f11898 100644
--- a/drivers/scsi/megaraid/megaraid_mbox.c
+++ b/drivers/scsi/megaraid/megaraid_mbox.c
@@ -2603,6 +2603,7 @@ static DEF_SCSI_QCMD(megaraid_queue_command)
list_for_each_entry_safe(scb, tmp, &adapter->pend_list, list) {
list_del_init(&scb->list); // from pending list
+ spin_unlock_irqrestore(PENDING_LIST_LOCK(adapter), flags);
if (scb->sno >= MBOX_MAX_SCSI_CMDS) {
con_log(CL_ANN, (KERN_WARNING
"megaraid: IOCTL packet with %d[%d:%d] being reset\n",
@@ -2630,6 +2631,7 @@ static DEF_SCSI_QCMD(megaraid_queue_command)
megaraid_dealloc_scb(adapter, scb);
}
+ spin_lock_irqsave(PENDING_LIST_LOCK(adapter), flags);
}
spin_unlock_irqrestore(PENDING_LIST_LOCK(adapter), flags);
--
1.9.1
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