The following commit has been merged into the locking/core branch of tip:
Commit-ID: 8a9d677a395703ef9075c91dd04066be8a553405
Gitweb: https://git.kernel.org/tip/8a9d677a395703ef9075c91dd04066be8a553405
Author: Ryo Takakura <ryotkkr98@xxxxxxxxx>
AuthorDate: Sat, 18 Jan 2025 14:49:00 +09:00
Committer: Boqun Feng <boqun.feng@xxxxxxxxx>
CommitterDate: Sun, 23 Feb 2025 18:24:46 -08:00
lockdep: Fix wait context check on softirq for PREEMPT_RT
Since commit 0c1d7a2c2d32 ("lockdep: Remove softirq accounting on
PREEMPT_RT."), the wait context test for mutex usage within
"in softirq context" fails as it references @softirq_context.
[ 0.184549] | wait context tests |
[ 0.184549] --------------------------------------------------------------------------
[ 0.184549] | rcu | raw | spin |mutex |
[ 0.184549] --------------------------------------------------------------------------
[ 0.184550] in hardirq context: ok | ok | ok | ok |
[ 0.185083] in hardirq context (not threaded): ok | ok | ok | ok |
[ 0.185606] in softirq context: ok | ok | ok |FAILED|
As a fix, add lockdep map for BH disabled section. This fixes the
issue by letting us catch cases when local_bh_disable() gets called
with preemption disabled where local_lock doesn't get acquired.
In the case of "in softirq context" selftest, local_bh_disable() was
being called with preemption disable as it's early in the boot.
Signed-off-by: Ryo Takakura <ryotkkr98@xxxxxxxxx>
Signed-off-by: Boqun Feng <boqun.feng@xxxxxxxxx>
Link: https://lore.kernel.org/r/20250118054900.18639-1-ryotkkr98@xxxxxxxxx
---
include/linux/bottom_half.h | 8 ++++++++
kernel/softirq.c | 12 ++++++++++++
2 files changed, 20 insertions(+)
diff --git a/include/linux/bottom_half.h b/include/linux/bottom_half.h
index fc53e0a..0640a14 100644
--- a/include/linux/bottom_half.h
+++ b/include/linux/bottom_half.h
@@ -4,6 +4,7 @@
#include <linux/instruction_pointer.h>
#include <linux/preempt.h>
+#include <linux/lockdep.h>
#if defined(CONFIG_PREEMPT_RT) || defined(CONFIG_TRACE_IRQFLAGS)
extern void __local_bh_disable_ip(unsigned long ip, unsigned int cnt);
@@ -15,8 +16,13 @@ static __always_inline void __local_bh_disable_ip(unsigned long ip, unsigned int
}
#endif
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+extern struct lockdep_map bh_lock_map;
+#endif
+
static inline void local_bh_disable(void)
{
+ lock_map_acquire_read(&bh_lock_map);
__local_bh_disable_ip(_THIS_IP_, SOFTIRQ_DISABLE_OFFSET);
}
@@ -25,11 +31,13 @@ extern void __local_bh_enable_ip(unsigned long ip, unsigned int cnt);
static inline void local_bh_enable_ip(unsigned long ip)
{
+ lock_map_release(&bh_lock_map);
__local_bh_enable_ip(ip, SOFTIRQ_DISABLE_OFFSET);
}
static inline void local_bh_enable(void)
{
+ lock_map_release(&bh_lock_map);
__local_bh_enable_ip(_THIS_IP_, SOFTIRQ_DISABLE_OFFSET);
}
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 4dae6ac..e864f9c 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -1073,3 +1073,15 @@ unsigned int __weak arch_dynirq_lower_bound(unsigned int from)
{
return from;
}
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+static struct lock_class_key bh_lock_key;
+struct lockdep_map bh_lock_map = {
+ .name = "local_bh",
+ .key = &bh_lock_key,
+ .wait_type_outer = LD_WAIT_FREE,
+ .wait_type_inner = LD_WAIT_CONFIG, /* PREEMPT_RT makes BH preemptible. */
+ .lock_type = LD_LOCK_PERCPU,
+};
+EXPORT_SYMBOL_GPL(bh_lock_map);
+#endif
|