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| author | Konstantin Belousov <kib@FreeBSD.org> | 2020-12-31 13:45:06 +0000 |
|---|---|---|
| committer | Konstantin Belousov <kib@FreeBSD.org> | 2021-01-10 02:41:20 +0000 |
| commit | a008bdeda3b8278fe600cf83ecf44acd1ccb30b6 (patch) | |
| tree | c1d6b034d6e17f273fee71ea54326521feee873f | |
| parent | ef739c7373d8b3833979ad471b31cb9e215411fd (diff) | |
| download | src-a008bdeda3b8278fe600cf83ecf44acd1ccb30b6.tar.gz src-a008bdeda3b8278fe600cf83ecf44acd1ccb30b6.zip | |
tty_wait_background: improve locking.
Increase the scope of the process group lock ownership. This ensures that
we are consistent in returning EIO for tty write from an orphan and delivery
of TTYOUT signals.
Reviewed by: jilles
Tested by: pho
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D27871
| -rw-r--r-- | sys/kern/tty.c | 33 |
1 files changed, 18 insertions, 15 deletions
diff --git a/sys/kern/tty.c b/sys/kern/tty.c index af4aebd18979..1f86507a6025 100644 --- a/sys/kern/tty.c +++ b/sys/kern/tty.c @@ -423,7 +423,7 @@ tty_is_ctty(struct tty *tp, struct proc *p) int tty_wait_background(struct tty *tp, struct thread *td, int sig) { - struct proc *p = td->td_proc; + struct proc *p; struct pgrp *pg; ksiginfo_t ksi; int error; @@ -431,8 +431,22 @@ tty_wait_background(struct tty *tp, struct thread *td, int sig) MPASS(sig == SIGTTIN || sig == SIGTTOU); tty_assert_locked(tp); + p = td->td_proc; for (;;) { + pg = p->p_pgrp; + PGRP_LOCK(pg); PROC_LOCK(p); + + /* + * pg may no longer be our process group. + * Re-check after locking. + */ + if (p->p_pgrp != pg) { + PROC_UNLOCK(p); + PGRP_UNLOCK(pg); + continue; + } + /* * The process should only sleep, when: * - This terminal is the controlling terminal @@ -445,6 +459,7 @@ tty_wait_background(struct tty *tp, struct thread *td, int sig) if (!tty_is_ctty(tp, p) || p->p_pgrp == tp->t_pgrp) { /* Allow the action to happen. */ PROC_UNLOCK(p); + PGRP_UNLOCK(pg); return (0); } @@ -452,13 +467,14 @@ tty_wait_background(struct tty *tp, struct thread *td, int sig) SIGISMEMBER(td->td_sigmask, sig)) { /* Only allow them in write()/ioctl(). */ PROC_UNLOCK(p); + PGRP_UNLOCK(pg); return (sig == SIGTTOU ? 0 : EIO); } - pg = p->p_pgrp; if ((p->p_flag & P_PPWAIT) != 0 || pg->pg_jobc == 0) { /* Don't allow the action to happen. */ PROC_UNLOCK(p); + PGRP_UNLOCK(pg); return (EIO); } PROC_UNLOCK(p); @@ -473,20 +489,7 @@ tty_wait_background(struct tty *tp, struct thread *td, int sig) ksi.ksi_signo = sig; sig = 0; } - PGRP_LOCK(pg); - - /* - * pg may no longer be our process group. - * Re-check after locking process group. - */ - PROC_LOCK(p); - if (p->p_pgrp != pg) { - PROC_UNLOCK(p); - PGRP_UNLOCK(pg); - continue; - } - PROC_UNLOCK(p); pgsignal(pg, ksi.ksi_signo, 1, &ksi); PGRP_UNLOCK(pg); |