Messages in this thread Patch in this message | | | From | Mitchel Humpherys <> | Subject | [PATCH] staging: ion: WARN when the handle kmap_cnt is going to wrap around | Date | Thu, 22 May 2014 17:51:21 -0700 |
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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
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