Commit 647da5f7 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

posix-timers: Move sequence logic into struct k_itimer 



The posix timer signal handling uses siginfo::si_sys_private for handling
the sequence counter check. That indirection is not longer required and the
sequence count value at signal queueing time can be stored in struct
k_itimer itself.

This removes the requirement of treating siginfo::si_sys_private special as
it's now always zero as the kernel does not touch it anymore.

Suggested-by: default avatarEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Acked-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
Link: https://lore.kernel.org/all/20241105064213.852619866@linutronix.de
parent c2a4796a

include/linux/posix-timers.h

+2 −0
Original line number Diff line number Diff line
@@ -162,6 +162,7 @@ static inline void posix_cputimers_init_work(void) { } 
 * @it_overrun:		The overrun counter for pending signals

 * @it_overrun_last:	The overrun at the time of the last delivered signal

 * @it_signal_seq:	Sequence count to control signal delivery

 * @it_sigqueue_seq:	The sequence count at the point where the signal was queued

 * @it_sigev_notify:	The notify word of sigevent struct for signal delivery

 * @it_interval:	The interval for periodic timers

 * @it_signal:		Pointer to the creators signal struct
@@ -184,6 +185,7 @@ struct k_itimer { 
	s64			it_overrun;

	s64			it_overrun_last;

	unsigned int		it_signal_seq;

	unsigned int		it_sigqueue_seq;

	int			it_sigev_notify;

	enum pid_type		it_pid_type;

	ktime_t			it_interval;

include/uapi/asm-generic/siginfo.h

+1 −1
Original line number Diff line number Diff line
@@ -46,7 +46,7 @@ union __sifields { 
		__kernel_timer_t _tid;	/* timer id */

		int _overrun;		/* overrun count */

		sigval_t _sigval;	/* same as below */

		int _sys_private;       /* not to be passed to user */

		int _sys_private;       /* Not used by the kernel. Historic leftover. Always 0. */

	} _timer;



	/* POSIX.1b signals */

kernel/signal.c

+3 −5
Original line number Diff line number Diff line
@@ -1976,12 +1976,10 @@ int posixtimer_send_sigqueue(struct k_itimer *tmr) 
		return -1;



	/*

	 * Update @q::info::si_sys_private for posix timer signals with

	 * sighand locked to prevent a race against dequeue_signal() which

	 * decides based on si_sys_private whether to invoke

	 * posixtimer_rearm() or not.

	 * Update @tmr::sigqueue_seq for posix timer signals with sighand

	 * locked to prevent a race against dequeue_signal().

	 */

	q->info.si_sys_private = tmr->it_signal_seq;

	tmr->it_sigqueue_seq = tmr->it_signal_seq;



	ret = 1; /* the signal is ignored */

	if (!prepare_signal(sig, t, false)) {

kernel/time/posix-timers.c

+1 −4
Original line number Diff line number Diff line
@@ -259,7 +259,7 @@ static bool __posixtimer_deliver_signal(struct kernel_siginfo *info, struct k_it 
	 * since the signal was queued. In either case, don't rearm and

	 * drop the signal.

	 */

	if (timr->it_signal_seq != info->si_sys_private || WARN_ON_ONCE(!timr->it_signal))

	if (timr->it_signal_seq != timr->it_sigqueue_seq || WARN_ON_ONCE(!timr->it_signal))

		return false;



	if (!timr->it_interval || WARN_ON_ONCE(timr->it_status != POSIX_TIMER_REQUEUE_PENDING))
@@ -297,9 +297,6 @@ bool posixtimer_deliver_signal(struct kernel_siginfo *info, struct sigqueue *tim 
	posixtimer_putref(timr);



	spin_lock(&current->sighand->siglock);



	/* Don't expose the si_sys_private value to userspace */

	info->si_sys_private = 0;

	return ret;

}