IB/qib: Fix potential deadlock with link down interrupt

There is a possibility of a deadlock due to the way locks are
acquired and released in qib_set_uevent_bits(). The function
qib_set_uevent_bits() is called in process context and it uses
spin_lock() and spin_unlock().  This same lock is acquired/released
in interrupt context which can lead to a deadlock when running on
the same cpu.

The fix is to replace spin_lock() and spin_unlock() with
spin_lock_irqsave() and spin_unlock_irqrestore() respectively in
qib_set_uevent_bits().

Signed-off-by: Mike Marciniszyn <mike.marciniszyn@qlogic.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/infiniband/hw/qib/qib_file_ops.c b/drivers/infiniband/hw/qib/qib_file_ops.c
index a94a46001745..26253039d2c7 100644
--- a/drivers/infiniband/hw/qib/qib_file_ops.c
+++ b/drivers/infiniband/hw/qib/qib_file_ops.c
@@ -1905,8 +1905,9 @@ int qib_set_uevent_bits(struct qib_pportdata *ppd, const int evtbit)
         struct qib_ctxtdata *rcd;
         unsigned ctxt;
         int ret = 0;
+        unsigned long flags;
 
-        spin_lock(&ppd->dd->uctxt_lock);
+        spin_lock_irqsave(&ppd->dd->uctxt_lock, flags);
         for (ctxt = ppd->dd->first_user_ctxt; ctxt < ppd->dd->cfgctxts;
              ctxt++) {
                 rcd = ppd->dd->rcd[ctxt];
@@ -1925,7 +1926,7 @@ int qib_set_uevent_bits(struct qib_pportdata *ppd, const int evtbit)
                 ret = 1;
                 break;
         }
-        spin_unlock(&ppd->dd->uctxt_lock);
+        spin_unlock_irqrestore(&ppd->dd->uctxt_lock, flags);
 
         return ret;
 }