From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932845AbcHNLBI (ORCPT ); Sun, 14 Aug 2016 07:01:08 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:51934 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933373AbcHNLBF (ORCPT ); Sun, 14 Aug 2016 07:01:05 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Linus Torvalds" , "=?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?=" Date: Sat, 13 Aug 2016 18:42:51 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 124/305] dma-debug: avoid spinlock recursion when disabling dma-debug In-Reply-To: X-SA-Exim-Connect-IP: 92.40.249.202 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.37-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Ville Syrjälä commit 3017cd63f26fc655d56875aaf497153ba60e9edf upstream. With netconsole (at least) the pr_err("... disablingn") call can recurse back into the dma-debug code, where it'll try to grab free_entries_lock again. Avoid the problem by doing the printk after dropping the lock. Link: http://lkml.kernel.org/r/1463678421-18683-1-git-send-email-ville.syrjala@linux.intel.com Signed-off-by: Ville Syrjälä Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings --- lib/dma-debug.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/lib/dma-debug.c +++ b/lib/dma-debug.c @@ -646,9 +646,9 @@ static struct dma_debug_entry *dma_entry spin_lock_irqsave(&free_entries_lock, flags); if (list_empty(&free_entries)) { - pr_err("DMA-API: debugging out of memory - disabling\n"); global_disable = true; spin_unlock_irqrestore(&free_entries_lock, flags); + pr_err("DMA-API: debugging out of memory - disabling\n"); return NULL; }