Fix memory leak in posix_clock_open()

If the clk ops.open() function returns an error, we don't release the
pccontext we allocated for this clock.

Re-organize the code slightly to make it all more obvious.
Reported-by: Rohit Keshri <rkeshri@redhat.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Fixes: 60c69466 ("posix-clock: introduce posix_clock_context concept")
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linuxfoundation.org>

kernel/time/posix-clock.c

@@ -129,15 +129,17 @@ static int posix_clock_open(struct inode *inode, struct file *fp)
 		goto out;
 	}
 	pccontext->clk = clk;
-	fp->private_data = pccontext;
-	if (clk->ops.open)
+	if (clk->ops.open) {
 		err = clk->ops.open(pccontext, fp->f_mode);
-	else
-		err = 0;
+		if (err) {
+			kfree(pccontext);
+			goto out;
+		}
+	}
 
-	if (!err) {
+	fp->private_data = pccontext;
 	get_device(clk->dev);
-	}
+	err = 0;
 out:
 	up_read(&clk->rwsem);
 	return err;