Fix a race condition in FASYNC handling

[linux-2.6-omap-h63xx.git] / fs / fcntl.c

diff --git a/fs/fcntl.c b/fs/fcntl.c
index ac4f7db9f13452790e4d41daa8e6fc9633506259..549daf8005fb5da252252d7e5bf0e73185250169 100644 (file)
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -19,6 +19,7 @@
 #include <linux/signal.h>
 #include <linux/rcupdate.h>
 #include <linux/pid_namespace.h>
+#include <linux/smp_lock.h>
 
 #include <asm/poll.h>
 #include <asm/siginfo.h>
@@ -175,6 +176,11 @@ static int setfl(int fd, struct file * filp, unsigned long arg)
        if (error)
                return error;
 
+       /*
+        * We still need a lock here for now to keep multiple FASYNC calls
+        * from racing with each other.
+        */
+       lock_kernel();
        if ((arg ^ filp->f_flags) & FASYNC) {
                if (filp->f_op && filp->f_op->fasync) {
                        error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0);
@@ -185,6 +191,7 @@ static int setfl(int fd, struct file * filp, unsigned long arg)
 
        filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK);
  out:
+       unlock_kernel();
        return error;
 }