The patch titled
relay: fix 4 off-by-one errors occuring when writing to a CPU buffer
has been added to the -mm tree. Its filename is
relay-fix-4-off-by-one-errors-occuring-when-writing-to-a-cpu-buffer.patch
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------------------------------------------------------
Subject: relay: fix 4 off-by-one errors occuring when writing to a CPU buffer
From: Tom Zanussi <tzanussi@xxxxxxxxx>
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@xxxxxxxxx>
Cc: Eduard - Gabriel Munteanu <eduard.munteanu@xxxxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
Cc: Jens Axboe <jens.axboe@xxxxxxxxxx>
Cc: Mathieu Desnoyers <compudj@xxxxxxxxxxxxxxxxxx>
Cc: Andrea Righi <righi.andrea@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/relay.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff -puN kernel/relay.c~relay-fix-4-off-by-one-errors-occuring-when-writing-to-a-cpu-buffer kernel/relay.c
--- a/kernel/relay.c~relay-fix-4-off-by-one-errors-occuring-when-writing-to-a-cpu-buffer
+++ a/kernel/relay.c
@@ -944,6 +944,10 @@ static void relay_file_read_consume(stru
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
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
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;
}
_
Patches currently in -mm which might be from tzanussi@xxxxxxxxx are
origin.patch
relay-fix-4-off-by-one-errors-occuring-when-writing-to-a-cpu-buffer.patch
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