linux-kernel - [PATCH] seq_file: fix condition while loop

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Date:   Thu, 31 Oct 2019 19:38:21 +0800
From:   Yi Li <yili@...hong.com>
To:     linux-fsdevel@...r.kernel.org
Cc:     yili@...hong.com, Yi Li <yilikernel@...il.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] seq_file: fix condition while loop

From: Yi Li <yilikernel@...il.com>

Use the break condition of loop body.
PTR_ERR has some meanings when p is illegal,and return 0 when p is null.
set the err = 0 on the next iteration if err > 0.

Signed-off-by: Yi Li <yilikernel@...il.com>
---
 fs/seq_file.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/fs/seq_file.c b/fs/seq_file.c
index 1600034..3796d4f 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -107,9 +107,10 @@ static int traverse(struct seq_file *m, loff_t offset)
 	}
 	p = m->op->start(m, &m->index);
 	while (p) {
-		error = PTR_ERR(p);
-		if (IS_ERR(p))
+		if (IS_ERR(p)) {
+			error = PTR_ERR(p);
 			break;
+		}
 		error = m->op->show(m, p);
 		if (error < 0)
 			break;
@@ -222,10 +223,11 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
 	/* we need at least one record in buffer */
 	m->from = 0;
 	p = m->op->start(m, &m->index);
-	while (1) {
-		err = PTR_ERR(p);
-		if (!p || IS_ERR(p))
+	while (p) {
+		if (IS_ERR(p)) {
+			err = PTR_ERR(p);
 			break;
+		}
 		err = m->op->show(m, p);
 		if (err < 0)
 			break;
@@ -233,6 +235,7 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
 			m->count = 0;
 		if (unlikely(!m->count)) {
 			p = m->op->next(m, p, &m->index);
+			err = 0;
 			continue;
 		}
 		if (m->count < m->size)
-- 
2.7.5