[PATCH] jbd: avoid kfree(NULL)

There are a couple of places where JBD has to check to see whether an unneeded
memory allocation was performed.  Usually it _was_ needed, so we end up
calling kfree(NULL).  We can micro-optimise that by checking the pointer
before calling kfree().

Thanks to Steven Rostedt <rostedt@goodmis.org> for identifying this.

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/fs/jbd/transaction.c b/fs/jbd/transaction.c
index ff75afe9b185cbb428a63495a3f0f247d73e9086..508b2ea91f43d090dca79617ac2060b5e36f635a 100644 (file)
--- a/fs/jbd/transaction.c
+++ b/fs/jbd/transaction.c
@@ -227,7 +227,8 @@ repeat_locked:
        spin_unlock(&transaction->t_handle_lock);
        spin_unlock(&journal->j_state_lock);
 out:
-       kfree(new_transaction);
+       if (unlikely(new_transaction))          /* It's usually NULL */
+               kfree(new_transaction);
        return ret;
 }
 
@@ -724,7 +725,8 @@ done:
        journal_cancel_revoke(handle, jh);
 
 out:
-       kfree(frozen_buffer);
+       if (unlikely(frozen_buffer))    /* It's usually NULL */
+               kfree(frozen_buffer);
 
        JBUFFER_TRACE(jh, "exit");
        return error;
@@ -903,7 +905,8 @@ repeat:
        jbd_unlock_bh_state(bh);
 out:
        journal_put_journal_head(jh);
-       kfree(committed_data);
+       if (unlikely(committed_data))
+               kfree(committed_data);
        return err;
 }