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 1cbfc16d0b3791a1896a82fbf724ef8c6b919f34..1ba298a9e15d670f6379322f36cd9d41f11d19a2 100644 (file)
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -646,9 +646,9 @@ 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;
        }