github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-07-28 01:55:51 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

sched: Use {READ,WRITE}_ONCE() for preempt_dynamic_mode

Browse Source 
Robots figured out you can read and write this concurrently and got
'upset'. Gemini even noted sched_dynamic_show() can generate
'confusing' output if it observed different values during the
printing.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260511120627.176946327@infradead.org
This commit is contained in:
Peter Zijlstra 2026-05-11 13:31:06 +02:00
parent 333f6f0e11
commit 7755700223
2 changed files with 11 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
kernel/sched/core.c
View File

@ -7979,7 +7979,7 @@ static void __sched_dynamic_update(int mode)
break;
}
preempt_dynamic_mode = mode;
WRITE_ONCE(preempt_dynamic_mode, mode);
}
void sched_dynamic_update(int mode)
@ -8020,12 +8020,13 @@ static void __init preempt_dynamic_init(void)
}
}
# define PREEMPT_MODEL_ACCESSOR(mode) \
bool preempt_model_##mode(void) \
{ \
WARN_ON_ONCE(preempt_dynamic_mode == preempt_dynamic_undefined); \
return preempt_dynamic_mode == preempt_dynamic_##mode; \
} \
# define PREEMPT_MODEL_ACCESSOR(mode) \
bool preempt_model_##mode(void) \
{ \
int mode = READ_ONCE(preempt_dynamic_mode); \
WARN_ON_ONCE(mode == preempt_dynamic_undefined); \
return mode == preempt_dynamic_##mode; \
} \
EXPORT_SYMBOL_GPL(preempt_model_##mode)
PREEMPT_MODEL_ACCESSOR(none);

5
kernel/sched/debug.c
View File

@ -281,6 +281,7 @@ static ssize_t sched_dynamic_write(struct file *filp, const char __user *ubuf,
static int sched_dynamic_show(struct seq_file *m, void *v)
{
int i = (IS_ENABLED(CONFIG_PREEMPT_RT) || IS_ENABLED(CONFIG_ARCH_HAS_PREEMPT_LAZY)) * 2;
int mode = READ_ONCE(preempt_dynamic_mode);
int j;
/* Count entries in NULL terminated preempt_modes */
@ -289,10 +290,10 @@ static int sched_dynamic_show(struct seq_file *m, void *v)
j -= !IS_ENABLED(CONFIG_ARCH_HAS_PREEMPT_LAZY);
for (; i < j; i++) {
if (preempt_dynamic_mode == i)
if (mode == i)
seq_puts(m, "(");
seq_puts(m, preempt_modes[i]);
if (preempt_dynamic_mode == i)
if (mode == i)
seq_puts(m, ")");
seq_puts(m, " ");