From: Borislav Petkov <bp@alien8.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Arnd Bergmann <arnd@arndb.de>,
Ayush Sawal <ayush.sawal@chelsio.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Rohit Maheshwari <rohitm@chelsio.com>,
Steven Rostedt <rostedt@goodmis.org>,
Vinay Kumar Yadav <vinay.yadav@chelsio.com>,
alsa-devel@alsa-project.org,
bcm-kernel-feedback-list@broadcom.com,
intel-gfx@lists.freedesktop.org,
intel-gvt-dev@lists.freedesktop.org, linux-alpha@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, linux-clk@vger.kernel.org,
linux-crypto@vger.kernel.org, linux-edac@vger.kernel.org,
linux-fbdev@vger.kernel.org, linux-hyperv@vger.kernel.org,
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Subject: [PATCH v0 42/42] notifier: Return an error when callback is already registered
Date: Mon, 8 Nov 2021 11:11:57 +0100 [thread overview]
Message-ID: <20211108101157.15189-43-bp@alien8.de> (raw)
In-Reply-To: <20211108101157.15189-1-bp@alien8.de>
From: Borislav Petkov <bp@suse.de>
The notifier registration routine doesn't return a proper error value
when a callback has already been registered, leading people to track
whether that registration has happened at the call site:
https://lore.kernel.org/amd-gfx/20210512013058.6827-1-mukul.joshi@amd.com/
Which is unnecessary.
Return -EEXIST to signal that case so that callers can act accordingly.
Enforce callers to check the return value, leading to loud screaming
during build:
arch/x86/kernel/cpu/mce/core.c: In function ‘mce_register_decode_chain’:
arch/x86/kernel/cpu/mce/core.c:167:2: error: ignoring return value of \
‘blocking_notifier_chain_register’, declared with attribute warn_unused_result [-Werror=unused-result]
blocking_notifier_chain_register(&x86_mce_decoder_chain, nb);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Drop the WARN too, while at it.
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ayush Sawal <ayush.sawal@chelsio.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Rohit Maheshwari <rohitm@chelsio.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Vinay Kumar Yadav <vinay.yadav@chelsio.com>
Cc: alsa-devel@alsa-project.org
Cc: bcm-kernel-feedback-list@broadcom.com
Cc: intel-gfx@lists.freedesktop.org
Cc: intel-gvt-dev@lists.freedesktop.org
Cc: linux-alpha@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-clk@vger.kernel.org
Cc: linux-crypto@vger.kernel.org
Cc: linux-edac@vger.kernel.org
Cc: linux-fbdev@vger.kernel.org
Cc: linux-hyperv@vger.kernel.org
Cc: linux-iio@vger.kernel.org
Cc: linux-leds@vger.kernel.org
Cc: linux-mips@vger.kernel.org
Cc: linux-parisc@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-remoteproc@vger.kernel.org
Cc: linux-renesas-soc@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: linux-scsi@vger.kernel.org
Cc: linux-sh@vger.kernel.org
Cc: linux-staging@lists.linux.dev
Cc: linux-tegra@vger.kernel.org
Cc: linux-um@lists.infradead.org
Cc: linux-usb@vger.kernel.org
Cc: linux-xtensa@linux-xtensa.org
Cc: netdev@vger.kernel.org
Cc: openipmi-developer@lists.sourceforge.net
Cc: rcu@vger.kernel.org
Cc: sparclinux@vger.kernel.org
Cc: x86@kernel.org
Cc: xen-devel@lists.xenproject.org
---
include/linux/notifier.h | 8 ++++----
kernel/notifier.c | 36 +++++++++++++++++++-----------------
2 files changed, 23 insertions(+), 21 deletions(-)
diff --git a/include/linux/notifier.h b/include/linux/notifier.h
index 87069b8459af..45cc5a8d0fd8 100644
--- a/include/linux/notifier.h
+++ b/include/linux/notifier.h
@@ -141,13 +141,13 @@ extern void srcu_init_notifier_head(struct srcu_notifier_head *nh);
#ifdef __KERNEL__
-extern int atomic_notifier_chain_register(struct atomic_notifier_head *nh,
+extern int __must_check atomic_notifier_chain_register(struct atomic_notifier_head *nh,
struct notifier_block *nb);
-extern int blocking_notifier_chain_register(struct blocking_notifier_head *nh,
+extern int __must_check blocking_notifier_chain_register(struct blocking_notifier_head *nh,
struct notifier_block *nb);
-extern int raw_notifier_chain_register(struct raw_notifier_head *nh,
+extern int __must_check raw_notifier_chain_register(struct raw_notifier_head *nh,
struct notifier_block *nb);
-extern int srcu_notifier_chain_register(struct srcu_notifier_head *nh,
+extern int __must_check srcu_notifier_chain_register(struct srcu_notifier_head *nh,
struct notifier_block *nb);
extern int atomic_notifier_chain_unregister(struct atomic_notifier_head *nh,
diff --git a/kernel/notifier.c b/kernel/notifier.c
index b8251dc0bc0f..451ef3f73ad2 100644
--- a/kernel/notifier.c
+++ b/kernel/notifier.c
@@ -20,13 +20,11 @@ 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;
- }
+ if (unlikely((*nl) == n))
+ return -EEXIST;
if (n->priority > (*nl)->priority)
break;
nl = &((*nl)->next);
@@ -134,10 +132,11 @@ 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)
+int __must_check
+atomic_notifier_chain_register(struct atomic_notifier_head *nh,
+ struct notifier_block *n)
{
unsigned long flags;
int ret;
@@ -216,10 +215,11 @@ 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)
+int __must_check
+blocking_notifier_chain_register(struct blocking_notifier_head *nh,
+ struct notifier_block *n)
{
int ret;
@@ -335,10 +335,11 @@ 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)
+int __must_check
+raw_notifier_chain_register(struct raw_notifier_head *nh,
+ struct notifier_block *n)
{
return notifier_chain_register(&nh->head, n);
}
@@ -406,10 +407,11 @@ 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)
+int __must_check
+srcu_notifier_chain_register(struct srcu_notifier_head *nh,
+ struct notifier_block *n)
{
int ret;
--
2.29.2
next prev parent reply other threads:[~2021-11-08 10:16 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-08 10:11 [PATCH v0 00/42] notifiers: Return an error when callback is already registered Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 01/42] x86: Check notifier registration return value Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 02/42] xen/x86: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 03/42] impi: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 04/42] clk: renesas: " Borislav Petkov
2021-11-08 14:12 ` Geert Uytterhoeven
2021-11-08 10:11 ` [PATCH v0 05/42] dca: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 06/42] firmware: " Borislav Petkov
2021-11-12 18:43 ` Cristian Marussi
2021-11-08 10:11 ` [PATCH v0 07/42] drm/i915: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 08/42] Drivers: hv: vmbus: " Borislav Petkov
2021-11-08 11:16 ` Wei Liu
2021-11-08 11:39 ` Borislav Petkov
2021-11-08 11:45 ` Wei Liu
2021-11-08 12:08 ` Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 09/42] iio: proximity: cros_ec: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 10/42] leds: trigger: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 11/42] misc: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 12/42] ethernet: chelsio: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 13/42] power: reset: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 14/42] remoteproc: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 15/42] scsi: target: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 16/42] USB: " Borislav Petkov
2021-11-08 14:05 ` Alan Stern
2021-11-08 14:09 ` Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 17/42] drivers: video: " Borislav Petkov
2021-11-08 11:16 ` Wei Liu
2021-11-08 10:11 ` [PATCH v0 18/42] drivers/xen: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 19/42] kernel/hung_task: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 20/42] rcu: " Borislav Petkov
2021-11-08 16:53 ` Paul E. McKenney
2021-11-08 10:11 ` [PATCH v0 21/42] tracing: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 22/42] net: fib_notifier: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 23/42] ASoC: soc-jack: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 24/42] staging: olpc_dcon: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 25/42] arch/um: " Borislav Petkov
2021-11-08 10:23 ` Johannes Berg
2021-11-08 10:48 ` Borislav Petkov
2021-11-08 10:56 ` Johannes Berg
2021-11-08 10:11 ` [PATCH v0 26/42] alpha: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 27/42] bus: brcmstb_gisb: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 28/42] soc: bcm: brcmstb: pm: pm-arm: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 29/42] arm64: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 30/42] soc/tegra: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 31/42] parisc: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 32/42] macintosh/adb: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 33/42] mips: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 34/42] powerpc: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 35/42] sh: " Borislav Petkov
2021-11-08 13:31 ` Geert Uytterhoeven
2021-11-08 13:49 ` Borislav Petkov
2021-11-08 14:03 ` Geert Uytterhoeven
2021-11-08 14:48 ` Sergey Shtylyov
2021-11-08 10:11 ` [PATCH v0 36/42] s390: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 37/42] sparc: " Borislav Petkov
2021-11-08 19:59 ` David Miller
2021-11-08 10:11 ` [PATCH v0 38/42] xtensa: " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 39/42] crypto: ccree - check " Borislav Petkov
2021-11-12 18:32 ` Cristian Marussi
2021-11-12 18:48 ` Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 40/42] EDAC/altera: Check " Borislav Petkov
2021-11-08 10:11 ` [PATCH v0 41/42] power: supply: ab8500: " Borislav Petkov
2021-11-08 10:11 ` Borislav Petkov [this message]
2021-11-08 14:07 ` [PATCH v0 42/42] notifier: Return an error when callback is already registered Geert Uytterhoeven
2021-11-08 14:21 ` Borislav Petkov
2021-11-08 15:25 ` Geert Uytterhoeven
2021-11-08 15:58 ` Borislav Petkov
2021-11-08 16:12 ` Geert Uytterhoeven
2021-11-08 16:21 ` Borislav Petkov
2021-11-08 20:59 ` Alan Stern
2021-11-08 21:18 ` Borislav Petkov
2021-11-08 10:19 ` [PATCH v0 00/42] notifiers: " Borislav Petkov
2021-11-08 14:17 ` Alan Stern
2021-11-08 14:24 ` Borislav Petkov
2021-11-08 14:35 ` Borislav Petkov
2021-11-08 16:23 ` Steven Rostedt
2021-11-08 16:29 ` Borislav Petkov
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