Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
posix-timers: Add a refcount to struct k_itimer
To cure the SIG_IGN handling for posix interval timers, the preallocated
sigqueue needs to be embedded into struct k_itimer to prevent life time
races of all sorts.
To make that work correctly it needs reference counting so that timer
deletion does not free the timer prematuraly when there is a signal queued
or delivered concurrently.
Add a rcuref to the posix timer part.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20241105064213.304756440@linutronix.de
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include/linux/posix-timers.h
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include/linux/posix-timers.h
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#include <linux/list.h>
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#include <linux/mutex.h>
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#include <linux/posix-timers_types.h>
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#include <linux/rcuref.h>
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#include <linux/spinlock.h>
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#include <linux/timerqueue.h>
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struct kernel_siginfo;
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struct task_struct;
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struct k_itimer;
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static inline clockid_t make_process_cpuclock(const unsigned int pid,
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const clockid_t clock)
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void posixtimer_rearm_itimer(struct task_struct *p);
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bool posixtimer_deliver_signal(struct kernel_siginfo *info);
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void posixtimer_free_timer(struct k_itimer *timer);
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/* Init task static initializer */
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#define INIT_CPU_TIMERBASE(b) { \
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u64 cpu_limit) { }
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static inline void posixtimer_rearm_itimer(struct task_struct *p) { }
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static inline bool posixtimer_deliver_signal(struct kernel_siginfo *info) { return false; }
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static inline void posixtimer_free_timer(struct k_itimer *timer) { }
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#endif
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#ifdef CONFIG_POSIX_CPU_TIMERS_TASK_WORK
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* @it_signal: Pointer to the creators signal struct
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* @it_pid: The pid of the process/task targeted by the signal
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* @it_process: The task to wakeup on clock_nanosleep (CPU timers)
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* @rcuref: Reference count for life time management
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* @sigq: Pointer to preallocated sigqueue
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* @it: Union representing the various posix timer type
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* internals.
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struct task_struct *it_process;
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};
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struct sigqueue *sigq;
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rcuref_t rcuref;
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union {
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struct {
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struct hrtimer timer;
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u64 *newval, u64 *oldval);
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int update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new);
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#ifdef CONFIG_POSIX_TIMERS
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static inline void posixtimer_putref(struct k_itimer *tmr)
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{
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if (rcuref_put(&tmr->rcuref))
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posixtimer_free_timer(tmr);
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}
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#endif /* !CONFIG_POSIX_TIMERS */
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#endif
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kernel/time/posix-timers.c
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kernel/time/posix-timers.c
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return NULL;
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}
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clear_siginfo(&tmr->sigq->info);
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rcuref_init(&tmr->rcuref, 1);
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return tmr;
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}
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static void posix_timer_free(struct k_itimer *tmr)
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void posixtimer_free_timer(struct k_itimer *tmr)
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{
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put_pid(tmr->it_pid);
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sigqueue_free(tmr->sigq);
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spin_lock(&hash_lock);
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hlist_del_rcu(&tmr->t_hash);
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spin_unlock(&hash_lock);
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posix_timer_free(tmr);
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posixtimer_putref(tmr);
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}
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static int common_timer_create(struct k_itimer *new_timer)
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*/
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new_timer_id = posix_timer_add(new_timer);
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if (new_timer_id < 0) {
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posix_timer_free(new_timer);
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posixtimer_free_timer(new_timer);
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return new_timer_id;
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}
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