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| author |   Borislav Petkov <bp@suse.de> | 2021-12-01 22:28:14 +0100 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2021-12-29 10:37:33 +0100 |
| commit | 5abb065dca7301de90b7c44bbcdc378e49e4d362 (patch) | |
| tree | 2bf97dbf77f38ff9e39921a1d79bb61e972f5951 /kernel/notifier.c | |
| parent | Linux 5.16-rc7 (diff) | |
| download | wireguard-linux-5abb065dca7301de90b7c44bbcdc378e49e4d362.tar.xz wireguard-linux-5abb065dca7301de90b7c44bbcdc378e49e4d362.zip | |
notifier: Return an error when a callback has already been registered
Return -EEXIST when a notifier callback has already been registered on a
notifier chain.
This should avoid any homegrown registration tracking at the callsite
like
https://lore.kernel.org/amd-gfx/20210512013058.6827-1-mukul.joshi@amd.com
for example.
This version is an alternative of
https://lore.kernel.org/r/20211108101157.15189-1-bp@alien8.de
which needed to touch every caller not checking the registration
routine's return value.
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/YcSWNdUBS8A2ZB3s@zn.tnic
Diffstat (limited to 'kernel/notifier.c')
| -rw-r--r-- | kernel/notifier.c | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/kernel/notifier.c b/kernel/notifier.c index b8251dc0bc0f..ba005ebf4730 100644 --- a/kernel/notifier.c +++ b/kernel/notifier.c @@ -20,12 +20,13 @@ BLOCKING_NOTIFIER_HEAD(reboot_notifier_list); */ static int notifier_chain_register(struct notifier_block **nl, - struct notifier_block *n) + struct notifier_block *n) { while ((*nl) != NULL) { if (unlikely((*nl) == n)) { - WARN(1, "double register detected"); - return 0; + WARN(1, "notifier callback %ps already registered", + n->notifier_call); + return -EEXIST; } if (n->priority > (*nl)->priority) break; @@ -134,7 +135,7 @@ static int notifier_call_chain_robust(struct notifier_block **nl, * * Adds a notifier to an atomic notifier chain. * - * Currently always returns zero. + * Returns 0 on success, %-EEXIST on error. */ int atomic_notifier_chain_register(struct atomic_notifier_head *nh, struct notifier_block *n) @@ -216,7 +217,7 @@ NOKPROBE_SYMBOL(atomic_notifier_call_chain); * Adds a notifier to a blocking notifier chain. * Must be called in process context. * - * Currently always returns zero. + * Returns 0 on success, %-EEXIST on error. */ int blocking_notifier_chain_register(struct blocking_notifier_head *nh, struct notifier_block *n) @@ -335,7 +336,7 @@ EXPORT_SYMBOL_GPL(blocking_notifier_call_chain); * Adds a notifier to a raw notifier chain. * All locking must be provided by the caller. * - * Currently always returns zero. + * Returns 0 on success, %-EEXIST on error. */ int raw_notifier_chain_register(struct raw_notifier_head *nh, struct notifier_block *n) @@ -406,7 +407,7 @@ EXPORT_SYMBOL_GPL(raw_notifier_call_chain); * Adds a notifier to an SRCU notifier chain. * Must be called in process context. * - * Currently always returns zero. + * Returns 0 on success, %-EEXIST on error. */ int srcu_notifier_chain_register(struct srcu_notifier_head *nh, struct notifier_block *n) |