Re: [patch V3 02/18] posix-timers: Initialise timer before adding it to the hash table

[Thomas Gleixner <tglx@linutronix.de>]

On Tue, Mar 11 2025 at 14:25, Frederic Weisbecker wrote:
> Le Sat, Mar 08, 2025 at 05:48:14PM +0100, Thomas Gleixner a écrit :
>>  
>> -static struct k_itimer *posix_timer_by_id(timer_t id)
>> +static inline struct signal_struct *posix_sig_owner(const struct k_itimer *timer)
>>  {
>> -	struct signal_struct *sig = current->signal;
>> -	struct hlist_head *head = &posix_timers_hashtable[hash(sig, id)];
>> +	unsigned long val = (unsigned long)timer->it_signal;
>
> When used from posix_timer_add() -> posix_timer_hashed(), it can race
> with another do_timer_create() that clears the BIT 0. It's fine but
> KCSAN is going to warn sooner or later.

Indeed

> It looks like a good candidate for data_race() ? Well, READ_ONCE() is
> fine too.

READ_ONCE() is the right thing to do.