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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: "Paul E. McKenney" <paulmck@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Boqun Feng <boqun.feng@gmail.com>,
	Matthew Wilcox <willy@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Sasha Levin <sashal@kernel.org>,
	frederic@kernel.org, quic_neeraju@quicinc.com,
	josh@joshtriplett.org, rcu@vger.kernel.org
Subject: [PATCH AUTOSEL 5.10 03/27] rcu: Make RCU_LOCKDEP_WARN() avoid early lockdep checks
Date: Sun, 26 Feb 2023 09:49:50 -0500	[thread overview]
Message-ID: <20230226145014.828855-3-sashal@kernel.org> (raw)
In-Reply-To: <20230226145014.828855-1-sashal@kernel.org>

From: "Paul E. McKenney" <paulmck@kernel.org>

[ Upstream commit 0cae5ded535c3a80aed94f119bbd4ee3ae284a65 ]

Currently, RCU_LOCKDEP_WARN() checks the condition before checking
to see if lockdep is still enabled.  This is necessary to avoid the
false-positive splats fixed by commit 3066820034b5dd ("rcu: Reject
RCU_LOCKDEP_WARN() false positives").  However, the current state can
result in false-positive splats during early boot before lockdep is fully
initialized.  This commit therefore checks debug_lockdep_rcu_enabled()
both before and after checking the condition, thus avoiding both sets
of false-positive error reports.

Reported-by: Steven Rostedt <rostedt@goodmis.org>
Reported-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reported-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 include/linux/rcupdate.h | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 095b3b39bd032..80e6c5bc50617 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -306,11 +306,18 @@ static inline int rcu_read_lock_any_held(void)
  * RCU_LOCKDEP_WARN - emit lockdep splat if specified condition is met
  * @c: condition to check
  * @s: informative message
+ *
+ * This checks debug_lockdep_rcu_enabled() before checking (c) to
+ * prevent early boot splats due to lockdep not yet being initialized,
+ * and rechecks it after checking (c) to prevent false-positive splats
+ * due to races with lockdep being disabled.  See commit 3066820034b5dd
+ * ("rcu: Reject RCU_LOCKDEP_WARN() false positives") for more detail.
  */
 #define RCU_LOCKDEP_WARN(c, s)						\
 	do {								\
 		static bool __section(".data.unlikely") __warned;	\
-		if ((c) && debug_lockdep_rcu_enabled() && !__warned) {	\
+		if (debug_lockdep_rcu_enabled() && (c) &&		\
+		    debug_lockdep_rcu_enabled() && !__warned) {		\
 			__warned = true;				\
 			lockdep_rcu_suspicious(__FILE__, __LINE__, s);	\
 		}							\
-- 
2.39.0


  parent reply	other threads:[~2023-02-26 14:58 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-26 14:49 [PATCH AUTOSEL 5.10 01/27] wifi: ath9k: Fix use-after-free in ath9k_hif_usb_disconnect() Sasha Levin
2023-02-26 14:49 ` [PATCH AUTOSEL 5.10 02/27] wifi: brcmfmac: Fix potential stack-out-of-bounds in brcmf_c_preinit_dcmds() Sasha Levin
2023-02-26 14:49 ` Sasha Levin [this message]
2023-02-26 14:49 ` [PATCH AUTOSEL 5.10 04/27] rcu: Suppress smp_processor_id() complaint in synchronize_rcu_expedited_wait() Sasha Levin
2023-02-26 14:49 ` [PATCH AUTOSEL 5.10 05/27] rcu-tasks: Make rude RCU-Tasks work well with CPU hotplug Sasha Levin
2023-02-26 14:49 ` [PATCH AUTOSEL 5.10 06/27] wifi: ath11k: debugfs: fix to work with multiple PCI devices Sasha Levin
2023-02-26 14:49 ` [PATCH AUTOSEL 5.10 07/27] thermal: intel: Fix unsigned comparison with less than zero Sasha Levin
2023-02-26 14:49 ` [PATCH AUTOSEL 5.10 08/27] timers: Prevent union confusion from unexpected restart_syscall() Sasha Levin
2023-02-26 14:49 ` [PATCH AUTOSEL 5.10 09/27] x86/bugs: Reset speculation control settings on init Sasha Levin
2023-02-26 14:49 ` [PATCH AUTOSEL 5.10 10/27] wifi: brcmfmac: ensure CLM version is null-terminated to prevent stack-out-of-bounds Sasha Levin
2023-02-26 14:49 ` [PATCH AUTOSEL 5.10 11/27] wifi: mt7601u: fix an integer underflow Sasha Levin
2023-02-26 14:49 ` [PATCH AUTOSEL 5.10 12/27] inet: fix fast path in __inet_hash_connect() Sasha Levin
2023-02-26 14:50 ` [PATCH AUTOSEL 5.10 13/27] ice: add missing checks for PF vsi type Sasha Levin
2023-02-26 14:50 ` [PATCH AUTOSEL 5.10 14/27] ACPI: Don't build ACPICA with '-Os' Sasha Levin
2023-02-26 14:50 ` [PATCH AUTOSEL 5.10 15/27] clocksource: Suspend the watchdog temporarily when high read latency detected Sasha Levin
2023-02-26 14:50 ` [PATCH AUTOSEL 5.10 16/27] crypto: hisilicon: Wipe entire pool on error Sasha Levin
2023-02-26 14:50 ` [PATCH AUTOSEL 5.10 17/27] netpoll: Remove 4s sleep during carrier detection Sasha Levin
2023-02-26 14:50 ` [PATCH AUTOSEL 5.10 18/27] net: bcmgenet: Add a check for oversized packets Sasha Levin
2023-02-26 14:50 ` [PATCH AUTOSEL 5.10 19/27] m68k: Check syscall_trace_enter() return code Sasha Levin
2023-02-26 14:50 ` [PATCH AUTOSEL 5.10 20/27] wifi: mt76: dma: free rx_head in mt76_dma_rx_cleanup Sasha Levin
2023-02-26 14:50 ` [PATCH AUTOSEL 5.10 21/27] ACPI: video: Fix Lenovo Ideapad Z570 DMI match Sasha Levin
2023-02-26 14:50 ` [PATCH AUTOSEL 5.10 22/27] net/mlx5: fw_tracer: Fix debug print Sasha Levin
2023-02-26 14:50 ` [PATCH AUTOSEL 5.10 23/27] coda: Avoid partial allocation of sig_inputArgs Sasha Levin
2023-02-26 14:50 ` [PATCH AUTOSEL 5.10 24/27] uaccess: Add minimum bounds check on kernel buffer size Sasha Levin
2023-02-26 14:50 ` [PATCH AUTOSEL 5.10 25/27] PM: EM: fix memory leak with using debugfs_lookup() Sasha Levin
2023-02-26 14:50 ` [PATCH AUTOSEL 5.10 26/27] Bluetooth: btusb: Add VID:PID 13d3:3529 for Realtek RTL8821CE Sasha Levin
2023-02-26 14:50 ` [PATCH AUTOSEL 5.10 27/27] devlink: health: Fix nla_nest_end in error flow Sasha Levin

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