From 4cdfe84b51420c9ac95c7133da2d4c8a191094af Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sun, 24 Aug 2008 07:45:33 -0400 Subject: [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 --- fs/seq_file.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'fs') 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; -- cgit v1.2.3