Author: kib
Date: Sun Jul 3 18:19:48 2016
New Revision: 302328
URL: https://svnweb.freebsd.org/changeset/base/302328
Log:
Provide helper macros to detect 'non-silent SBDRY' state and to
calculate appropriate return value for stops. Simplify the code by
using them.
Fix typo in sig_suspend_threads(). The thread which sleep must be
aborted is td2. (*)
In issignal(), when handling stopping signal for thread in
TD_SBDRY_INTR state, do not stop, this is wrong and fires assert.
This is yet another place where execution should be forced out of
SBDRY-protected region. For such case, return -1 from issignal() and
translate it to corresponding error code in sleepq_catch_signals().
Assert that other consumers of cursig() are not affected by the new
return value. (*)
Micro-optimize, mostly VFS and VOP methods, by avoiding calling the
functions when SIGDEFERSTOP_NOP non-change is requested. (**)
Reported and tested by: pho (*)
Requested by: bde (**)
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Approved by: re (gjb)
Modified:
head/sys/kern/kern_sig.c
head/sys/kern/kern_thread.c
head/sys/kern/subr_sleepqueue.c
head/sys/sys/proc.h
head/sys/sys/signalvar.h
Modified: head/sys/kern/kern_sig.c
==============================================================================
--- head/sys/kern/kern_sig.c Sun Jul 3 17:52:21 2016 (r302327)
+++ head/sys/kern/kern_sig.c Sun Jul 3 18:19:48 2016 (r302328)
@@ -1251,6 +1251,7 @@ kern_sigtimedwait(struct thread *td, sig
mtx_lock(&ps->ps_mtx);
sig = cursig(td);
mtx_unlock(&ps->ps_mtx);
+ KASSERT(sig >= 0, ("sig %d", sig));
if (sig != 0 && SIGISMEMBER(waitset, sig)) {
if (sigqueue_get(&td->td_sigqueue, sig, ksi) != 0 ||
sigqueue_get(&p->p_sigqueue, sig, ksi) != 0) {
@@ -1512,8 +1513,10 @@ kern_sigsuspend(struct thread *td, sigse
/* void */;
thread_suspend_check(0);
mtx_lock(&p->p_sigacts->ps_mtx);
- while ((sig = cursig(td)) != 0)
+ while ((sig = cursig(td)) != 0) {
+ KASSERT(sig >= 0, ("sig %d", sig));
has_sig += postsig(sig);
+ }
mtx_unlock(&p->p_sigacts->ps_mtx);
}
PROC_UNLOCK(p);
@@ -2476,11 +2479,9 @@ sig_suspend_threads(struct thread *td, s
*/
KASSERT(!TD_IS_SUSPENDED(td2),
("thread with deferred stops suspended"));
- if ((td2->td_flags & (TDF_SERESTART |
- TDF_SEINTR)) != 0 && sending) {
- wakeup_swapper |= sleepq_abort(td,
- (td2->td_flags & TDF_SERESTART)
- != 0 ? ERESTART : EINTR);
+ if (TD_SBDRY_INTR(td2) && sending) {
+ wakeup_swapper |= sleepq_abort(td2,
+ TD_SBDRY_ERRNO(td2));
}
} else if (!TD_IS_SUSPENDED(td2)) {
thread_suspend_one(td2);
@@ -2628,7 +2629,7 @@ sigdeferstop_curr_flags(int cflags)
* accesses below.
*/
int
-sigdeferstop(int mode)
+sigdeferstop_impl(int mode)
{
struct thread *td;
int cflags, nflags;
@@ -2655,11 +2656,11 @@ sigdeferstop(int mode)
panic("sigdeferstop: invalid mode %x", mode);
break;
}
- if (cflags != nflags) {
- thread_lock(td);
- td->td_flags = (td->td_flags & ~cflags) | nflags;
- thread_unlock(td);
- }
+ if (cflags == nflags)
+ return (SIGDEFERSTOP_VAL_NCHG);
+ thread_lock(td);
+ td->td_flags = (td->td_flags & ~cflags) | nflags;
+ thread_unlock(td);
return (cflags);
}
@@ -2670,11 +2671,12 @@ sigdeferstop(int mode)
* either via ast() or a subsequent interruptible sleep.
*/
void
-sigallowstop(int prev)
+sigallowstop_impl(int prev)
{
struct thread *td;
int cflags;
+ KASSERT(prev != SIGDEFERSTOP_VAL_NCHG, ("failed sigallowstop"));
KASSERT((prev & ~(TDF_SBDRY | TDF_SEINTR | TDF_SERESTART)) == 0,
("sigallowstop: incorrect previous mode %x", prev));
td = curthread;
@@ -2835,6 +2837,11 @@ issignal(struct thread *td)
(p->p_pgrp->pg_jobc == 0 &&
prop & SA_TTYSTOP))
break; /* == ignore */
+ if (TD_SBDRY_INTR(td)) {
+ KASSERT((td->td_flags & TDF_SBDRY) != 0,
+ ("lost TDF_SBDRY"));
+ return (-1);
+ }
mtx_unlock(&ps->ps_mtx);
WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK,
&p->p_mtx.lock_object, "Catching SIGSTOP");
Modified: head/sys/kern/kern_thread.c
==============================================================================
--- head/sys/kern/kern_thread.c Sun Jul 3 17:52:21 2016 (r302327)
+++ head/sys/kern/kern_thread.c Sun Jul 3 18:19:48 2016 (r302328)
@@ -894,7 +894,7 @@ thread_suspend_check(int return_instead)
{
struct thread *td;
struct proc *p;
- int wakeup_swapper, r;
+ int wakeup_swapper;
td = curthread;
p = td->td_proc;
@@ -927,21 +927,10 @@ thread_suspend_check(int return_instead)
if ((td->td_flags & TDF_SBDRY) != 0) {
KASSERT(return_instead,
("TDF_SBDRY set for unsafe thread_suspend_check"));
- switch (td->td_flags & (TDF_SEINTR | TDF_SERESTART)) {
- case 0:
- r = 0;
- break;
- case TDF_SEINTR:
- r = EINTR;
- break;
- case TDF_SERESTART:
- r = ERESTART;
- break;
- default:
- panic("both TDF_SEINTR and TDF_SERESTART");
- break;
- }
- return (r);
+ KASSERT((td->td_flags & (TDF_SEINTR | TDF_SERESTART)) !=
+ (TDF_SEINTR | TDF_SERESTART),
+ ("both TDF_SEINTR and TDF_SERESTART"));
+ return (TD_SBDRY_INTR(td) ? TD_SBDRY_ERRNO(td) : 0);
}
/*
Modified: head/sys/kern/subr_sleepqueue.c
==============================================================================
--- head/sys/kern/subr_sleepqueue.c Sun Jul 3 17:52:21 2016
(r302327)
+++ head/sys/kern/subr_sleepqueue.c Sun Jul 3 18:19:48 2016
(r302328)
@@ -453,7 +453,16 @@ sleepq_catch_signals(void *wchan, int pr
ps = p->p_sigacts;
mtx_lock(&ps->ps_mtx);
sig = cursig(td);
- if (sig == 0) {
+ if (sig == -1) {
+ mtx_unlock(&ps->ps_mtx);
+ KASSERT((td->td_flags & TDF_SBDRY) != 0, ("lost TDF_SBDRY"));
+ KASSERT(TD_SBDRY_INTR(td),
+ ("lost TDF_SERESTART of TDF_SEINTR"));
+ KASSERT((td->td_flags & (TDF_SEINTR | TDF_SERESTART)) !=
+ (TDF_SEINTR | TDF_SERESTART),
+ ("both TDF_SEINTR and TDF_SERESTART"));
+ ret = TD_SBDRY_ERRNO(td);
+ } else if (sig == 0) {
mtx_unlock(&ps->ps_mtx);
ret = thread_suspend_check(1);
MPASS(ret == 0 || ret == EINTR || ret == ERESTART);
Modified: head/sys/sys/proc.h
==============================================================================
--- head/sys/sys/proc.h Sun Jul 3 17:52:21 2016 (r302327)
+++ head/sys/sys/proc.h Sun Jul 3 18:19:48 2016 (r302328)
@@ -511,6 +511,11 @@ do {
\
#define TD_SET_RUNQ(td) (td)->td_state = TDS_RUNQ
#define TD_SET_CAN_RUN(td) (td)->td_state = TDS_CAN_RUN
+#define TD_SBDRY_INTR(td) \
+ (((td)->td_flags & (TDF_SEINTR | TDF_SERESTART)) != 0)
+#define TD_SBDRY_ERRNO(td) \
+ (((td)->td_flags & TDF_SEINTR) != 0 ? EINTR : ERESTART)
+
/*
* Process structure.
*/
Modified: head/sys/sys/signalvar.h
==============================================================================
--- head/sys/sys/signalvar.h Sun Jul 3 17:52:21 2016 (r302327)
+++ head/sys/sys/signalvar.h Sun Jul 3 18:19:48 2016 (r302328)
@@ -337,9 +337,29 @@ extern struct mtx sigio_lock;
#define SIGDEFERSTOP_EINTR 3 /* ignore STOPs, return EINTR */
#define SIGDEFERSTOP_ERESTART 4 /* ignore STOPs, return ERESTART */
+#define SIGDEFERSTOP_VAL_NCHG (-1) /* placeholder indicating no state
change */
+int sigdeferstop_impl(int mode);
+void sigallowstop_impl(int prev);
+
+static inline int
+sigdeferstop(int mode)
+{
+
+ if (mode == SIGDEFERSTOP_NOP)
+ return (SIGDEFERSTOP_VAL_NCHG);
+ return (sigdeferstop_impl(mode));
+}
+
+static inline void
+sigallowstop(int prev)
+{
+
+ if (prev == SIGDEFERSTOP_VAL_NCHG)
+ return;
+ sigallowstop_impl(prev);
+}
+
int cursig(struct thread *td);
-int sigdeferstop(int mode);
-void sigallowstop(int prev);
void execsigs(struct proc *p);
void gsignal(int pgid, int sig, ksiginfo_t *ksi);
void killproc(struct proc *p, char *why);
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