From e97e1267e9faa6480898a1fc34c8e40d74d702f2 Mon Sep 17 00:00:00 2001 From: Alex Elder Date: Wed, 6 Aug 2014 16:08:59 -0700 Subject: [PATCH] printk: tweak do_syslog() to match comments In do_syslog() there's a path used by kmsg_poll() and kmsg_read() that only needs to know whether there's any data available to read (and not its size). These callers only check for non-zero return. As a shortcut, do_syslog() returns the difference between what has been logged and what has been "seen." The comments say that the "count of records" should be returned but it's not. Instead it returns (log_next_idx - syslog_idx), which is a difference between buffer offsets--and the result could be negative. The behavior is the same (it'll be zero or not in the same cases), but the count of records is more meaningful and it matches what the comments say. So change the code to return that. Signed-off-by: Alex Elder Cc: Petr Mladek Cc: Jan Kara Cc: Joe Perches Cc: John Stultz Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/printk/printk.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index f855ec3..ec3bfb0 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -1351,7 +1351,7 @@ int do_syslog(int type, char __user *buf, int len, bool from_file) * for pending data, not the size; return the count of * records, not the length. */ - error = log_next_idx - syslog_idx; + error = log_next_seq - syslog_seq; } else { u64 seq = syslog_seq; u32 idx = syslog_idx; -- 2.7.4