lkml.org 
[lkml]   [2014]   [May]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] staging: ion: WARN when the handle kmap_cnt is going to wrap around
Date
There are certain client bugs (double unmap, for example) that can cause
the handle->kmap_cnt (an unsigned int) to wrap around from zero. This
causes problems when the handle is destroyed because we have:

while (handle->kmap_cnt)
ion_handle_kmap_put(handle);

which takes a long time to complete when kmap_cnt starts at ~0 and can
result in a watchdog timeout.

WARN and bail when kmap_cnt is about to wrap around from zero.

Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>
---
drivers/staging/android/ion/ion.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
index 3d5bf14722..f55f61a4cc 100644
--- a/drivers/staging/android/ion/ion.c
+++ b/drivers/staging/android/ion/ion.c
@@ -626,6 +626,10 @@ static void ion_handle_kmap_put(struct ion_handle *handle)
{
struct ion_buffer *buffer = handle->buffer;

+ if (!handle->kmap_cnt) {
+ WARN(1, "%s: Double unmap detected! bailing...\n", __func__);
+ return;
+ }
handle->kmap_cnt--;
if (!handle->kmap_cnt)
ion_buffer_kmap_put(buffer);
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
hosted by The Linux Foundation


\
 
 \ /
  Last update: 2014-05-23 03:41    [W:0.044 / U:2.424 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site