svn commit: r346640 - in projects/fuse2/sys: fs/fuse kern

[Alan Somers]

Author: asomers
Date: Wed Apr 24 15:54:18 2019
New Revision: 346640
URL: https://svnweb.freebsd.org/changeset/base/346640

Log:
  fusefs: interruptibility improvements suggested by kib
  
  * Block stop signals in fticket_wait_answer
  * Hold ps_mtx while checking signal disposition
  * style(9) changes
  
  PR:		346357
  Reported by:	kib
  Sponsored by:	The FreeBSD Foundation

Modified:
  projects/fuse2/sys/fs/fuse/fuse_ipc.c
  projects/fuse2/sys/kern/kern_sig.c

Modified: projects/fuse2/sys/fs/fuse/fuse_ipc.c
==============================================================================
--- projects/fuse2/sys/fs/fuse/fuse_ipc.c	Wed Apr 24 15:35:29 2019	(r346639)
+++ projects/fuse2/sys/fs/fuse/fuse_ipc.c	Wed Apr 24 15:54:18 2019	(r346640)
@@ -430,10 +430,11 @@ fticket_wait_answer(struct fuse_ticket *ftick)
 {
 	struct thread *td = curthread;
 	sigset_t blockedset, oldset;
-	int err = 0;
+	int err = 0, stops_deferred;
 	struct fuse_data *data;
-	SIGEMPTYSET(blockedset);
 
+	SIGEMPTYSET(blockedset);
+	stops_deferred = sigdeferstop(SIGDEFERSTOP_SILENT);
 	kern_sigprocmask(td, SIG_BLOCK, NULL, &oldset, 0);
 
 	fuse_lck_mtx_lock(ftick->tk_aw_mtx);
@@ -476,6 +477,7 @@ retry:
 		 * or EAGAIN to the interrupt.
 		 */
 		int sig;
+		bool fatal;
 
 		SDT_PROBE2(fusefs, , ipc, trace, 4,
 			"fticket_wait_answer: interrupt");
@@ -485,11 +487,12 @@ retry:
 		PROC_LOCK(td->td_proc);
 		mtx_lock(&td->td_proc->p_sigacts->ps_mtx);
 		sig = cursig(td);
+		fatal = sig_isfatal(td->td_proc, sig);
 		mtx_unlock(&td->td_proc->p_sigacts->ps_mtx);
 		PROC_UNLOCK(td->td_proc);
 
 		fuse_lck_mtx_lock(ftick->tk_aw_mtx);
-		if (!sig_isfatal(td->td_proc, sig)) {
+		if (!fatal) {
 			/* 
 			 * Block the just-delivered signal while we wait for an
 			 * interrupt response
@@ -512,6 +515,7 @@ out:
 		err = ENXIO;
 	}
 	fuse_lck_mtx_unlock(ftick->tk_aw_mtx);
+	sigallowstop(stops_deferred);
 
 	return err;
 }

Modified: projects/fuse2/sys/kern/kern_sig.c
==============================================================================
--- projects/fuse2/sys/kern/kern_sig.c	Wed Apr 24 15:35:29 2019	(r346639)
+++ projects/fuse2/sys/kern/kern_sig.c	Wed Apr 24 15:54:18 2019	(r346640)
@@ -929,16 +929,16 @@ osigreturn(struct thread *td, struct osigreturn_args *
 #endif
 #endif /* COMPAT_43 */
 
-/* Will this signal be fatal to the current process ? */
+/* Would this signal be fatal to the current process, if it were caught ? */
 bool
 sig_isfatal(struct proc *p, int sig)
 {
 	intptr_t act;
+	int prop;
 
+	mtx_assert(&p->p_sigacts->ps_mtx, MA_OWNED);
 	act = (intptr_t)p->p_sigacts->ps_sigact[_SIG_IDX(sig)];
 	if ((intptr_t)SIG_DFL == act) {
-		int prop;
-
 		prop = sigprop(sig);
 		return (0 != (prop & (SIGPROP_KILL | SIGPROP_CORE)));
 	} else {