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authorAl Viro <viro@zeniv.linux.org.uk>2008-08-24 07:45:33 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2008-08-25 01:18:10 -0400
commit4cdfe84b51420c9ac95c7133da2d4c8a191094af (patch)
treeb15ad9cd9d9db1117be13b5da1b00399ee544c70
parent59af1584bf33810639cb98d79856021253e2177c (diff)
downloadlinux-4cdfe84b51420c9ac95c7133da2d4c8a191094af.tar.gz
[PATCH] deal with the first call of ->show() generating no output
seq_read() has a subtle bug - we want the first loop there to go until at least one *non-empty* record had fit entirely into buffer. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r--fs/seq_file.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/fs/seq_file.c b/fs/seq_file.c
index 5d54205e486..bd20f7f5a93 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -108,9 +108,9 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
goto Done;
}
/* we need at least one record in buffer */
+ pos = m->index;
+ p = m->op->start(m, &pos);
while (1) {
- pos = m->index;
- p = m->op->start(m, &pos);
err = PTR_ERR(p);
if (!p || IS_ERR(p))
break;
@@ -119,6 +119,11 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
break;
if (unlikely(err))
m->count = 0;
+ if (unlikely(!m->count)) {
+ p = m->op->next(m, p, &pos);
+ m->index = pos;
+ continue;
+ }
if (m->count < m->size)
goto Fill;
m->op->stop(m, p);
@@ -128,6 +133,8 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
goto Enomem;
m->count = 0;
m->version = 0;
+ pos = m->index;
+ p = m->op->start(m, &pos);
}
m->op->stop(m, p);
m->count = 0;