procfs: Use generic_file_llseek in /proc/kcore

/proc/kcore has no llseek and then falls down to use default_llseek.
This is racy against read_kcore() that directly manipulates fpos
but it doesn't hold the bkl there so using it in llseek doesn't
protect anything.

Let's use generic_file_llseek() instead.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: John Kacur <jkacur@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>

diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index b442dac..3964532 100644 (file)
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -557,6 +557,7 @@ static int open_kcore(struct inode *inode, struct file *filp)
 static const struct file_operations proc_kcore_operations = {
        .read           = read_kcore,
        .open           = open_kcore,
+       .llseek         = generic_file_llseek,
 };
 
 #ifdef CONFIG_MEMORY_HOTPLUG