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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index eb43517bf261e3fb9c108b4f3878bd9e6313310f..c32437f6be61f232c065b7f532c242f4e5bbc163 100644 (file)
--- 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;
        }