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@xxxxxxxxxxxxxx> Acked-by: Colin Cross <ccross@xxxxxxxxxxx> --- Resending since I missed a few folks on the original. Also retaining Colin's Acked-by. --- 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 _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel