From: Ville Syrjälä <ville.syrjala@linux.intel.com>
Date: Thu, 26 May 2016 22:16:25 +0000 (-0700)
Subject: dma-debug: avoid spinlock recursion when disabling dma-debug
X-Git-Tag: firefly_0821_release~176^2~4^2~42^2~10
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=7d0b494532b703da654f96389804f491a6594bbb;p=firefly-linux-kernel-4.4.55.git

dma-debug: avoid spinlock recursion when disabling dma-debug

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 <ville.syrjala@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index 4a1515f4b452..51a76af25c66 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -657,9 +657,9 @@ static struct dma_debug_entry *dma_entry_alloc(void)
 	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;
 	}