git: 008b2e65442a - main - Make stop_all_proc_block interruptible to avoid deadlock with parallel suspension
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Date: Mon, 13 Jun 2022 19:33:38 UTC
The branch main has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=008b2e65442a0d65bc5be9ca625616ddfa6f9ce2 commit 008b2e65442a0d65bc5be9ca625616ddfa6f9ce2 Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2022-04-30 23:29:25 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2022-06-13 19:30:03 +0000 Make stop_all_proc_block interruptible to avoid deadlock with parallel suspension If we try to single-thread a process which thread entered procctl(REAP_KILL_SUBTREE), and sleeping waiting for us unlocking stop_all_proc_blocker, we must be able to finish single-threading. This requires the sleep to be interruptible. Reported and tested by: pho Reviewed by: markj Sponsored by: The FreeBSD Foundation MFC after: 2 weeks Differential revision: https://reviews.freebsd.org/D35310 --- sys/kern/kern_proc.c | 7 ++++--- sys/kern/kern_procctl.c | 4 ++-- sys/sys/proc.h | 2 +- 3 files changed, 7 insertions(+), 6 deletions(-) diff --git a/sys/kern/kern_proc.c b/sys/kern/kern_proc.c index 6796d672afd7..67299472231a 100644 --- a/sys/kern/kern_proc.c +++ b/sys/kern/kern_proc.c @@ -3399,10 +3399,10 @@ static SYSCTL_NODE(_kern_proc, KERN_PROC_VM_LAYOUT, vm_layout, CTLFLAG_RD | static struct sx stop_all_proc_blocker; SX_SYSINIT(stop_all_proc_blocker, &stop_all_proc_blocker, "sapblk"); -void +bool stop_all_proc_block(void) { - sx_xlock(&stop_all_proc_blocker); + return (sx_xlock_sig(&stop_all_proc_blocker) == 0); } void @@ -3426,7 +3426,8 @@ stop_all_proc(void) int r, gen; bool restart, seen_stopped, seen_exiting, stopped_some; - stop_all_proc_block(); + if (!stop_all_proc_block()) + return; cp = curproc; allproc_loop: diff --git a/sys/kern/kern_procctl.c b/sys/kern/kern_procctl.c index 6919fac71c5a..b6e48b46bb5c 100644 --- a/sys/kern/kern_procctl.c +++ b/sys/kern/kern_procctl.c @@ -1063,8 +1063,8 @@ kern_procctl(struct thread *td, idtype_t idtype, id_t id, int com, void *data) sapblk = false; if (cmd_info->sapblk != NULL) { sapblk = cmd_info->sapblk(td, data); - if (sapblk) - stop_all_proc_block(); + if (sapblk && !stop_all_proc_block()) + return (ERESTART); } switch (cmd_info->lock_tree) { diff --git a/sys/sys/proc.h b/sys/sys/proc.h index cdb9cc17945d..5521f8321e2b 100644 --- a/sys/sys/proc.h +++ b/sys/sys/proc.h @@ -1238,7 +1238,7 @@ void thread_unlink(struct thread *td); void thread_unsuspend(struct proc *p); void thread_wait(struct proc *p); -void stop_all_proc_block(void); +bool stop_all_proc_block(void); void stop_all_proc_unblock(void); void stop_all_proc(void); void resume_all_proc(void);