path: root/builtin/fetch-pack.c
diff options
authorJunio C Hamano <>2011-03-29 17:06:19 (GMT)
committerJunio C Hamano <>2011-03-29 19:20:22 (GMT)
commit44d8dc54e73e8010c4bdf57a422fc8d5ce709029 (patch)
tree98cb72c7df0efc0d35538b26422053d13078ee1b /builtin/fetch-pack.c
parent066bf4c2e43c7fb40405843e49f809431314865d (diff)
Fix potential local deadlock during fetch-pack
The fetch-pack/upload-pack protocol relies on the underlying transport (local pipe or TCP socket) to have enough slack to allow one window worth of data in flight without blocking the writer. Traditionally we always relied on being able to have two windows of 32 "have"s in flight (roughly 3k bytes) to stream. The recent "progressive-stride" change allows "fetch-pack" to send up to 1024 "have"s without reading any response from "upload-pack". The outgoing pipe of "upload-pack" can be clogged with many ACK and NAK that are unread, while "fetch-pack" is still stuffing its outgoing pipe with more "have"s, leading to a deadlock. Revert the change unless we are in stateless rpc (aka smart-http) mode, as using a large window full of "have"s is still a good way to help reduce the number of back-and-forth, and there is no buffering issue there (it is strictly "ping-pong" without an overlap). Signed-off-by: Junio C Hamano <>
Diffstat (limited to 'builtin/fetch-pack.c')
1 files changed, 5 insertions, 4 deletions
diff --git a/builtin/fetch-pack.c b/builtin/fetch-pack.c
index 3c2c940..147d67d 100644
--- a/builtin/fetch-pack.c
+++ b/builtin/fetch-pack.c
@@ -219,16 +219,17 @@ static void send_request(int fd, struct strbuf *buf)
#define INITIAL_FLUSH 16
+#define PIPESAFE_FLUSH 32
#define LARGE_FLUSH 1024
static int next_flush(int count)
- if (count < INITIAL_FLUSH * 2)
- count += INITIAL_FLUSH;
- else if (count < LARGE_FLUSH)
+ int flush_limit = args.stateless_rpc ? LARGE_FLUSH : PIPESAFE_FLUSH;
+ if (count < flush_limit)
count <<= 1;
- count += LARGE_FLUSH;
+ count += flush_limit;
return count;