9os

commit a074501aeb8c9764eb13c50813cf51fcf5142792
parent 44a2f95676a50d4f9503f994064f3b52cb072a5f
Author: Dimitris Papastamos <dimitris.papastamos@arm.com>
Date:   Tue, 19 Feb 2019 11:27:14 +0000

Take a lock when accessing fdset[]

Change-Id: I143a33ac043c921ef156cdcb4bfd59ca51823f9d
Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com>

Diffstat:
M
drivers/dev.c
 | 
31
++++++++++++++++++-------------

1 file changed, 18 insertions(+), 13 deletions(-)
diff --git a/drivers/dev.c b/drivers/dev.c
@@ -9,20 +9,27 @@
 
 static Chan fdset[NR_CHANS];
 static Chan slash;
+static mutex_t chanlock;
 
 static Chan *
-newchan(void)
+newchan(unsigned char type)
 {
-	Chan *c, *lim;
+	Chan *c = NULL;
+	int i;
 
-	lim = &fdset[NR_CHANS];
-	for (c = fdset; c < lim; c++) {
-		if (c->type == NODEV)
-			return c;
+	lock(&chanlock);
+	for (i = 0; i < NR_CHANS; i++) {
+		if (fdset[i].type == NODEV) {
+			c = &fdset[i];
+			c->type = type;
+			break;
+		}
 	}
+	unlock(&chanlock);
 
-	errno = ENOMEM;
-	return NULL;
+	if (!c)
+		errno = ENOMEM;
+	return c;
 }
 
 static Chan *
@@ -105,9 +112,9 @@ static void
 chanclose(Chan *c)
 {
 	c->qid = 0;
-	c->type = NODEV;
 	c->dev = 0;
 	c->offset = 0;
+	c->type = NODEV;
 }
 
 Chan *
@@ -163,11 +170,10 @@ notfound:
 Chan *
 devclone(Chan *c, Chan *nc)
 {
-	if (!nc && (nc = newchan()) == NULL)
+	if (!nc && (nc = newchan(c->type)) == NULL)
 		return NULL;
 
 	nc->qid = c->qid;
-	nc->type = c->type;
 	nc->dev = c->dev;
 	nc->mode = c->mode;
 	nc->offset = c->offset;
@@ -183,10 +189,9 @@ devattach(const char *spec, int id)
 
 	if ((type = devtype(id)) < 0)
 		return NULL;
-	if ((c = newchan()) == NULL)
+	if ((c = newchan(devtype(id))) == NULL)
 		return NULL;
 	c->qid = CHDIR;
-	c->type = devtype(id);
 
 	return c;
 }