| commit | 53ecfba259f54b6967a35d19f4a564e3bc07997f | |
| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | |
| Tue, 14 Sep 2010 00:24:21 +0000 (13 17:24 -0700) | ||
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | |
| Thu, 23 Sep 2010 16:15:01 +0000 (23 09:15 -0700) | ||
| tree | eaaeebe2a38abe1a401a0d2d40181abaefa80d48 | treesnapshot (tar.gz zip) |
| parent | 829f8ed2c963df7c23d1c644db6c4387eb1601fa | commitdiff |
rcu: only one evaluation of arg in rcu_dereference_check() unless sparse
The current version of the __rcu_access_pointer(), __rcu_dereference_check(),
and __rcu_dereference_protected() macros evaluate their "p" argument
three times, not counting typeof()s. This is bad news if that argument
contains a side effect. This commit therefore evaluates this argument
only once in normal kernel builds. However, the straightforward approach
defeats sparse's RCU-pointer checking, so when __CHECKER__ is defined,
the additional pair of evaluations of the "p" argument are performed in
order to permit sparse to detect misuse of RCU-protected pointers.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
The current version of the __rcu_access_pointer(), __rcu_dereference_check(),
and __rcu_dereference_protected() macros evaluate their "p" argument
three times, not counting typeof()s. This is bad news if that argument
contains a side effect. This commit therefore evaluates this argument
only once in normal kernel builds. However, the straightforward approach
defeats sparse's RCU-pointer checking, so when __CHECKER__ is defined,
the additional pair of evaluations of the "p" argument are performed in
order to permit sparse to detect misuse of RCU-protected pointers.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
| include/linux/rcupdate.h | diffblobblamehistory |