From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f44.google.com (mail-pa0-f44.google.com [209.85.220.44]) by kanga.kvack.org (Postfix) with ESMTP id ED5316B0035 for ; Fri, 23 May 2014 16:01:37 -0400 (EDT) Received: by mail-pa0-f44.google.com with SMTP id ld10so4531850pab.31 for ; Fri, 23 May 2014 13:01:37 -0700 (PDT) Received: from smtp.codeaurora.org (smtp.codeaurora.org. [198.145.11.231]) by mx.google.com with ESMTPS id yf6si5309438pbc.37.2014.05.23.13.01.36 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 23 May 2014 13:01:37 -0700 (PDT) From: Mitchel Humpherys Subject: [RESEND PATCH] staging: ion: WARN when the handle kmap_cnt is going to wrap around Date: Fri, 23 May 2014 13:01:22 -0700 Message-Id: <1400875282-17892-1-git-send-email-mitchelh@codeaurora.org> Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org, Colin Cross , John Stultz , Greg Kroah-Hartman Cc: devel@driverdev.osuosl.org, Android Kernel Team , linux-kernel@vger.kernel.org, Mitchel Humpherys 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 Acked-by: Colin Cross --- 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org