tracing: Move mutex to protect against resetting of seq data

The iter->seq can be reset outside the protection of the mutex. So can
reading of user data. Move the mutex up to the beginning of the function.

Fixes: d7350c3f45694 ("tracing/core: make the read callbacks reentrants")
Cc: stable@vger.kernel.org # 2.6.30+
Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

path: root/rnd.h

#ifndef RND_H
#define RND_H

#define HIG_ENTROPY_SOURCE	"/dev/random"
#define LOW_ENTROPY_SOURCE	"/dev/urandom"

/* secrand is not really secure, but the name only suggests it's better to use
 * than rand(3) when transferring bytes over the network in non-security
 * critical structure members. secrand() is only used to fill up salts actually.
 */
extern int secrand(void);
extern void gen_key_bytes(unsigned char *area, size_t len);

#endif /* RND_H */