diff options
| author | Maksim Davydov <davydov-max@yandex-team.ru> | 2025-03-25 11:58:07 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2025-03-25 10:16:50 +0100 |
| commit | 0e1ff67d164be45e8ddfea5aaf5803224ede0805 (patch) | |
| tree | 616042b07ae438046e060566dd05a85161ee9748 | |
| parent | 2df0c02dab829dd89360d98a8a1abaa026ef5798 (diff) | |
x86/split_lock: Simplify reenabling
When split_lock_mitigate is disabled, each CPU needs its own delayed_work
structure. They are used to reenable split lock detection after its
disabling. But delayed_work structure must be correctly initialized after
its allocation.
Current implementation uses deferred initialization that makes the
split lock handler code unclear. The code can be simplified a bit
if the initialization is moved to the appropriate initcall.
sld_setup() is called before setup_per_cpu_areas(), thus it can't be used
for this purpose, so introduce an independent initcall for
the initialization.
[ mingo: Simplified the 'work' assignment line a bit more. ]
Signed-off-by: Maksim Davydov <davydov-max@yandex-team.ru>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250325085807.171885-1-davydov-max@yandex-team.ru
| -rw-r--r-- | arch/x86/kernel/cpu/bus_lock.c | 35 |
1 files changed, 24 insertions, 11 deletions
diff --git a/arch/x86/kernel/cpu/bus_lock.c b/arch/x86/kernel/cpu/bus_lock.c index 97222efb4d2a..237faf7e700c 100644 --- a/arch/x86/kernel/cpu/bus_lock.c +++ b/arch/x86/kernel/cpu/bus_lock.c @@ -201,6 +201,26 @@ static void __split_lock_reenable(struct work_struct *work) static DEFINE_PER_CPU(struct delayed_work, sl_reenable); /* + * Per-CPU delayed_work can't be statically initialized properly because + * the struct address is unknown. Thus per-CPU delayed_work structures + * have to be initialized during kernel initialization and after calling + * setup_per_cpu_areas(). + */ +static int __init setup_split_lock_delayed_work(void) +{ + unsigned int cpu; + + for_each_possible_cpu(cpu) { + struct delayed_work *work = per_cpu_ptr(&sl_reenable, cpu); + + INIT_DELAYED_WORK(work, __split_lock_reenable); + } + + return 0; +} +pure_initcall(setup_split_lock_delayed_work); + +/* * If a CPU goes offline with pending delayed work to re-enable split lock * detection then the delayed work will be executed on some other CPU. That * handles releasing the buslock_sem, but because it executes on a @@ -219,15 +239,16 @@ static int splitlock_cpu_offline(unsigned int cpu) static void split_lock_warn(unsigned long ip) { - struct delayed_work *work = NULL; + struct delayed_work *work; int cpu; + unsigned int saved_sld_mitigate = READ_ONCE(sysctl_sld_mitigate); if (!current->reported_split_lock) pr_warn_ratelimited("#AC: %s/%d took a split_lock trap at address: 0x%lx\n", current->comm, current->pid, ip); current->reported_split_lock = 1; - if (sysctl_sld_mitigate) { + if (saved_sld_mitigate) { /* * misery factor #1: * sleep 10ms before trying to execute split lock. @@ -240,18 +261,10 @@ static void split_lock_warn(unsigned long ip) */ if (down_interruptible(&buslock_sem) == -EINTR) return; - work = &sl_reenable_unlock; } cpu = get_cpu(); - - if (!work) { - work = this_cpu_ptr(&sl_reenable); - /* Deferred initialization of per-CPU struct */ - if (!work->work.func) - INIT_DELAYED_WORK(work, __split_lock_reenable); - } - + work = saved_sld_mitigate ? &sl_reenable_unlock : per_cpu_ptr(&sl_reenable, cpu); schedule_delayed_work_on(cpu, work, 2); /* Disable split lock detection on this CPU to make progress */ |