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| author | Nadia Derbey <Nadia.Derbey@bull.net> | 2008-04-29 01:00:45 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-04-29 08:06:13 -0700 |
| commit | 6546bc4279241e8fa432de1bb63a4f6f791fd669 (patch) | |
| tree | 308f5c1621b1019a44800622ffc468a372f09434 /kernel/notifier.c | |
| parent | 91cfb2b4b57816de0c96de417b3238249f0b125f (diff) | |
| download | lwn-6546bc4279241e8fa432de1bb63a4f6f791fd669.tar.gz lwn-6546bc4279241e8fa432de1bb63a4f6f791fd669.zip | |
ipc: re-enable msgmni automatic recomputing msgmni if set to negative
The enhancement as asked for by Yasunori: if msgmni is set to a negative
value, register it back into the ipcns notifier chain.
A new interface has been added to the notification mechanism:
notifier_chain_cond_register() registers a notifier block only if not already
registered. With that new interface we avoid taking care of the states
changes in procfs.
Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Mingming Cao <cmm@us.ibm.com>
Cc: Pierre Peiffer <pierre.peiffer@bull.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/notifier.c')
| -rw-r--r-- | kernel/notifier.c | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/kernel/notifier.c b/kernel/notifier.c index 643360d1bb14..823be11584ef 100644 --- a/kernel/notifier.c +++ b/kernel/notifier.c @@ -31,6 +31,21 @@ static int notifier_chain_register(struct notifier_block **nl, return 0; } +static int notifier_chain_cond_register(struct notifier_block **nl, + struct notifier_block *n) +{ + while ((*nl) != NULL) { + if ((*nl) == n) + return 0; + if (n->priority > (*nl)->priority) + break; + nl = &((*nl)->next); + } + n->next = *nl; + rcu_assign_pointer(*nl, n); + return 0; +} + static int notifier_chain_unregister(struct notifier_block **nl, struct notifier_block *n) { @@ -205,6 +220,29 @@ int blocking_notifier_chain_register(struct blocking_notifier_head *nh, EXPORT_SYMBOL_GPL(blocking_notifier_chain_register); /** + * blocking_notifier_chain_cond_register - Cond add notifier to a blocking notifier chain + * @nh: Pointer to head of the blocking notifier chain + * @n: New entry in notifier chain + * + * Adds a notifier to a blocking notifier chain, only if not already + * present in the chain. + * Must be called in process context. + * + * Currently always returns zero. + */ +int blocking_notifier_chain_cond_register(struct blocking_notifier_head *nh, + struct notifier_block *n) +{ + int ret; + + down_write(&nh->rwsem); + ret = notifier_chain_cond_register(&nh->head, n); + up_write(&nh->rwsem); + return ret; +} +EXPORT_SYMBOL_GPL(blocking_notifier_chain_cond_register); + +/** * blocking_notifier_chain_unregister - Remove notifier from a blocking notifier chain * @nh: Pointer to head of the blocking notifier chain * @n: Entry to remove from notifier chain |