[patch 2/4] net: use mutex_is_locked() for ASSERT_RTNL()

[akpm]

From: Andrew Morton <[EMAIL PROTECTED]>

ASSERT_RTNL() uses mutex_trylock(), but it's better to use mutex_is_locked().

Make that change, and remove rtnl_trylock() altogether.

(not tested yet!)

Cc: "David S. Miller" <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
---

 drivers/net/cxgb3/cxgb3_main.c |    3 +--
 include/linux/rtnetlink.h      |    5 ++---
 net/core/rtnetlink.c           |    7 ++++---
 3 files changed, 7 insertions(+), 8 deletions(-)

diff -puN 
drivers/net/cxgb3/cxgb3_main.c~net-use-mutex_is_locked-for-assert_rtnl 
drivers/net/cxgb3/cxgb3_main.c
--- a/drivers/net/cxgb3/cxgb3_main.c~net-use-mutex_is_locked-for-assert_rtnl
+++ a/drivers/net/cxgb3/cxgb3_main.c
@@ -2191,7 +2191,7 @@ static void check_t3b2_mac(struct adapte
 {
        int i;
 
-       if (!rtnl_trylock())    /* synchronize with ifdown */
+       if (rtnl_is_locked())   /* synchronize with ifdown */
                return;
 
        for_each_port(adapter, i) {
@@ -2219,7 +2219,6 @@ static void check_t3b2_mac(struct adapte
                        p->mac.stats.num_resets++;
                }
        }
-       rtnl_unlock();
 }
 
 
diff -puN include/linux/rtnetlink.h~net-use-mutex_is_locked-for-assert_rtnl 
include/linux/rtnetlink.h
--- a/include/linux/rtnetlink.h~net-use-mutex_is_locked-for-assert_rtnl
+++ a/include/linux/rtnetlink.h
@@ -751,14 +751,13 @@ extern void rtmsg_ifinfo(int type, struc
 /* RTNL is used as a global lock for all changes to network configuration  */
 extern void rtnl_lock(void);
 extern void rtnl_unlock(void);
-extern int rtnl_trylock(void);
+extern int rtnl_is_locked(void);
 
 extern void rtnetlink_init(void);
 extern void __rtnl_unlock(void);
 
 #define ASSERT_RTNL() do { \
-       if (unlikely(rtnl_trylock())) { \
-               rtnl_unlock(); \
+       if (unlikely(!rtnl_is_locked())) { \
                printk(KERN_ERR "RTNL: assertion failed at %s (%d)\n", \
                       __FILE__,  __LINE__); \
                dump_stack(); \
diff -puN net/core/rtnetlink.c~net-use-mutex_is_locked-for-assert_rtnl 
net/core/rtnetlink.c
--- a/net/core/rtnetlink.c~net-use-mutex_is_locked-for-assert_rtnl
+++ a/net/core/rtnetlink.c
@@ -77,9 +77,10 @@ void rtnl_unlock(void)
        netdev_run_todo();
 }
 
-int rtnl_trylock(void)
+/* Return non-zero if rtnl_mutex is presently held */
+int rtnl_is_locked(void)
 {
-       return mutex_trylock(&rtnl_mutex);
+       return mutex_is_locked(&rtnl_mutex);
 }
 
 int rtattr_parse(struct rtattr *tb[], int maxattr, struct rtattr *rta, int len)
@@ -1424,7 +1425,7 @@ EXPORT_SYMBOL(rtattr_parse);
 EXPORT_SYMBOL(__rtattr_parse_nested_compat);
 EXPORT_SYMBOL(rtnetlink_put_metrics);
 EXPORT_SYMBOL(rtnl_lock);
-EXPORT_SYMBOL(rtnl_trylock);
+EXPORT_SYMBOL(rtnl_is_locked);
 EXPORT_SYMBOL(rtnl_unlock);
 EXPORT_SYMBOL(rtnl_unicast);
 EXPORT_SYMBOL(rtnl_notify);
_
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