diff mbox

[dpdk-dev,v4,8/9] mem: fix statement having no effect

Message ID 437feb67375bd2e52f66cce8b33e01c55f03160b.1524848343.git.anatoly.burakov@intel.com (mailing list archive)
State Accepted, archived
Headers

Checks

Context Check Description
ci/checkpatch success coding style OK
ci/Intel-compilation fail apply patch file failure

Commit Message

Anatoly Burakov April 27, 2018, 5:07 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>
Acked-by: Bruce Richardson <bruce.richardson@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 a40cfd3..672a1be 100644
--- a/lib/librte_eal/linuxapp/eal/eal_memalloc.c
+++ b/lib/librte_eal/linuxapp/eal/eal_memalloc.c
@@ -504,7 +504,12 @@  alloc_seg(struct rte_memseg *ms, void *addr, int socket_id,
 	if (!internal_config.single_file_segments)
 		close(fd);
 
-	*(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;