[PATCH 3.12 48/56] dma-debug: avoid spinlock recursion when disabling dma-debug

[Jiri Slaby]

From: Ville SyrjÃlà <ville.syrjala@xxxxxxxxxxxxxxx>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

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@xxxxxxxxxxxxxxx
Signed-off-by: Ville SyrjÃlà <ville.syrjala@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 lib/dma-debug.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index eb43517bf261..c32437f6be61 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -445,9 +445,9 @@ 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;
 	}
 
-- 
2.9.0