9os

commit 17bcf6b69b7e5b169e4616e2e66516bd06a84cc4
parent ba49132121060c8e6a494d2e47d94a5e50ffb54f
Author: Roberto E. Vargas Caballero <roberto.vargas@midokura.com>
Date:   Sun, 13 Nov 2022 09:51:04 +0100

os9: Fix deadlocks in procfs

There were several cases where tasks were not unlocked
after being adquired.

Diffstat:
M
src/os9/dev/devproc.c
 | 
24
+++++++++++++++---------
M
src/os9/proc.c
 | 
3
++-

2 files changed, 17 insertions(+), 10 deletions(-)
diff --git a/src/os9/dev/devproc.c b/src/os9/dev/devproc.c
@@ -27,32 +27,36 @@ static int
 procfsgen(Chan *c, Dirtab *tab, int ntab, int n, Dir *dir)
 {
 	Task *tp;
+	int ret = 0;
 	char nam[NAMELEN];
 
 	n = getntask(n, &tp);
 	if (n <= 0)
-		return 0;
+		return -1;
+	if (tp->tid == -1)
+		goto novalid;
 
 	ksnprint(nam, NAMELEN, "%d", tp->tid);
 	mkentry(c, dir,
 		nam, 0,
 		QID(CHDIR, 0, PATH(Qtaskdir, tp->tid)),
 	        O_READ);
+	ret = 1;
+
+novalid:
 	unlock(&tp->m);
 
-	return 1;
+	return ret;
 }
 
 static int
 taskgen(Chan *c, Dirtab *tab, int ntab, int n, Dir *dir)
 {
-	int tid = TASK(c->qid);
-
-	if (!devgen(c, tasktab, NELEM(tasktab), n, dir)) 
-		return 0;
-	dir->qid.path = PATH(dir->qid.path, tid);
+	int r, tid = TASK(c->qid);
 
-	return 1;
+	if ((r = devgen(c, tasktab, NELEM(tasktab), n, dir)) == 1)
+		dir->qid.path = PATH(dir->qid.path, tid);
+	return r;
 }
 
 static int
@@ -82,7 +86,7 @@ taskattrread(Chan *c, void *buf, int n)
 	char tmp[1024];
 
 	if ((tp = gettask(TASK(c->qid))) == NULL)
-		panic("");
+		panic("taskattrread:gettask");
 
 	len = ksnprint(tmp,
 	               sizeof(tmp),
@@ -102,6 +106,7 @@ taskattrread(Chan *c, void *buf, int n)
 	               tp->period,
 	               tp->capacity,
 	               tp->deadline);
+	unlock(&tp->m);
 
 	if (len == sizeof(tmp))
 		panic("temporary buffer too short");
@@ -139,6 +144,7 @@ taskstatusread(Chan *c, void *buf, int n)
 	               states[tp->state],
 	               tp->affinity,
 	               tp->retainprio);
+	unlock(&tp->m);
 
 	if (len == sizeof(tmp))
 		panic("temporary buffer too short");
diff --git a/src/os9/proc.c b/src/os9/proc.c
@@ -36,8 +36,9 @@ iproc(void)
 	}
 	freel = tasktab;
 
-	if (!kproc(initfn))
+	if ((tp = kproc(initfn)) == NULL)
 		panic("init task failed");
+	unlock(&tp->m);
 }
 
 void