zattr_show: check if zattr->s_op are present

If a zio object declares a set of read only attributes and it doesn't need s_op->info_get(), it can avoid the s_op assignment, so zattr_show now checks if s_op is defined before calling it. Signed-off-by: Federico Vaga <federico.vaga@gmail.com> Acked-by: Alessandro Rubini <rubini@gnudd.com>

zattr_show: check if zattr->s_op are present
If a zio object declares a set of read only attributes and it doesn't need s_op->info_get(), it can avoid the s_op assignment, so zattr_show now checks if s_op is defined before calling it. Signed-off-by: Federico Vaga <federico.vaga@gmail.com> Acked-by: Alessandro Rubini <rubini@gnudd.com>
29091a80 · Federico Vaga · Alessandro Rubini · fdb09d3e · 29091a80
Commit 29091a80 authored Feb 13, 2012 by Federico Vaga Committed by Alessandro Rubini Mar 14, 2012
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zio-sys.c zio-sys.c +4 -0

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--- a/zio-sys.c
+++ b/zio-sys.c
@@ -698,6 +698,9 @@ static ssize_t zattr_show(struct kobject *kobj, struct attribute *attr,
 		return sprintf(buf, "%d\n",
 			  !((*__get_flag(to_zio_head(kobj))) & ZIO_DISABLED));

+	/* only read attributes can avoid s_op declaration */
+	if (!zattr->s_op)
+		goto out;
 	if (zattr->s_op->info_get) {
 		lock = __get_spinlock(to_zio_head(kobj));
 		spin_lock(lock);
@@ -706,6 +709,7 @@ static ssize_t zattr_show(struct kobject *kobj, struct attribute *attr,
 		if (err)
 			return err;
 	}
+out:
 	len = sprintf(buf, "%i\n", zattr->value);
 	return len;
 }