From: Sebastian Sanchez <sebastian.sanchez@intel.com>
Date: Thu, 8 Dec 2016 03:33:33 +0000 (-0800)
Subject: IB/hfi1: Remove critical section gap in sc_buffer_alloc()
X-Git-Tag: v4.10-rc1~97^2~3^2~15
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=9b86071c5ef7a8c0a0d6d541cb79df5a8b115d91;p=karo-tx-linux.git

IB/hfi1: Remove critical section gap in sc_buffer_alloc()

In sc_buffer_alloc(), the sc->alloc_lock is released
before calling sc_release_update(), and it is reacquired
after the function call. This causes CPU lock trading.
Fix it by not dropping the lock before calling
sc_release_update().

Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Sebastian Sanchez <sebastian.sanchez@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
---

diff --git a/drivers/infiniband/hw/hfi1/pio.c b/drivers/infiniband/hw/hfi1/pio.c
index 86a7f365b624..75c4dea84c4b 100644
--- a/drivers/infiniband/hw/hfi1/pio.c
+++ b/drivers/infiniband/hw/hfi1/pio.c
@@ -1419,9 +1419,7 @@ retry:
 			(sc->fill - sc->alloc_free);
 		if (blocks > avail) {
 			/* still no room, actively update */
-			spin_unlock_irqrestore(&sc->alloc_lock, flags);
 			sc_release_update(sc);
-			spin_lock_irqsave(&sc->alloc_lock, flags);
 			sc->alloc_free = ACCESS_ONCE(sc->free);
 			trycount++;
 			goto retry;