diff mbox

[dpdk-dev,08/10] mem: fix statement having no effect

Message ID 11a30142e2e9ebbed985743dfd5c97a8821e724c.1523977588.git.anatoly.burakov@intel.com (mailing list archive)
State Superseded, archived
Delegated to: Thomas Monjalon
Headers

Checks

Context Check Description
ci/checkpatch success coding style OK
ci/Intel-compilation success Compilation OK

Commit Message

Anatoly Burakov April 17, 2018, 3:50 p.m. UTC 
  Coverity reports these lines as having no effect. Technically, we do
want for those lines to have no effect, however they would've likely
been optimized out. Add volatile qualifiers to ensure the code has
effects.

Coverity issue: 272608

Fixes: 582bed1e1d1d ("mem: support mapping hugepages at runtime")
Cc: anatoly.burakov@intel.com

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
---
 lib/librte_eal/linuxapp/eal/eal_memalloc.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
diff mbox

Patch

diff --git a/lib/librte_eal/linuxapp/eal/eal_memalloc.c b/lib/librte_eal/linuxapp/eal/eal_memalloc.c
index 6a75e5b..655c69e 100644
--- a/lib/librte_eal/linuxapp/eal/eal_memalloc.c
+++ b/lib/librte_eal/linuxapp/eal/eal_memalloc.c
@@ -503,7 +503,12 @@  alloc_seg(struct rte_memseg *ms, void *addr, int socket_id,
 			(unsigned int)(alloc_sz >> 20));
 		goto mapped;
 	}
-	*(int *)addr = *(int *)addr;
+	/* we need to trigger a write to the page to enforce page fault and
+	 * ensure that page is accessible to us, but we can't overwrite value
+	 * that is already there, so read the old value, and write itback.
+	 * kernel populates the page with zeroes initially.
+	 */
+	*(volatile int *)addr = *(volatile int *)addr;
 
 	ms->addr = addr;
 	ms->hugepage_sz = alloc_sz;