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authorTom Zanussi <tzanussi@gmail.com>2008-08-05 13:01:10 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-08-05 14:33:46 -0700
commit32194450330be327f3b25bf6b66298bd122599e9 (patch)
tree48efcfe62b2c09396f4d9e03839f53e1577a4019 /kernel/relay.c
parent60cadec9da7b6c91aca51f408c828f7e74a68379 (diff)
downloadvexpress-lsk-32194450330be327f3b25bf6b66298bd122599e9.tar.gz
relay: fix "full buffer with exactly full last subbuffer" accounting problem
In relay's current read implementation, if the buffer is completely full but hasn't triggered the buffer-full condition (i.e. the last write didn't cross the subbuffer boundary) and the last subbuffer is exactly full, the subbuffer accounting code erroneously finds nothing available. This patch fixes the problem. Signed-off-by: Tom Zanussi <tzanussi@gmail.com> Cc: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Jens Axboe <jens.axboe@oracle.com> Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org> Cc: Andrea Righi <righi.andrea@gmail.com> Cc: <stable@kernel.org> [2.6.25.x, 2.6.26.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/relay.c')
-rw-r--r--kernel/relay.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/kernel/relay.c b/kernel/relay.c
index 04006ef970b..8d13a7855c0 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -944,6 +944,10 @@ static void relay_file_read_consume(struct rchan_buf *buf,
size_t n_subbufs = buf->chan->n_subbufs;
size_t read_subbuf;
+ if (buf->subbufs_produced == buf->subbufs_consumed &&
+ buf->offset == buf->bytes_consumed)
+ return;
+
if (buf->bytes_consumed + bytes_consumed > subbuf_size) {
relay_subbufs_consumed(buf->chan, buf->cpu, 1);
buf->bytes_consumed = 0;
@@ -975,6 +979,8 @@ static int relay_file_read_avail(struct rchan_buf *buf, size_t read_pos)
relay_file_read_consume(buf, read_pos, 0);
+ consumed = buf->subbufs_consumed;
+
if (unlikely(buf->offset > subbuf_size)) {
if (produced == consumed)
return 0;
@@ -993,8 +999,12 @@ static int relay_file_read_avail(struct rchan_buf *buf, size_t read_pos)
if (consumed > produced)
produced += n_subbufs * subbuf_size;
- if (consumed == produced)
+ if (consumed == produced) {
+ if (buf->offset == subbuf_size &&
+ buf->subbufs_produced > buf->subbufs_consumed)
+ return 1;
return 0;
+ }
return 1;
}