Date: Mon, 1 Aug 2011 12:05:18 GMT From: Mathieu <sigsys@gmail.com> To: freebsd-gnats-submit@FreeBSD.org Subject: bin/159352: accidental busy-waiting loop in fetch(3) Message-ID: <201108011205.p71C5Ieo092633@red.freebsd.org> Resent-Message-ID: <201108011210.p71CA6kx074537@freefall.freebsd.org>
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>Number: 159352
>Category: bin
>Synopsis: accidental busy-waiting loop in fetch(3)
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Mon Aug 01 12:10:05 UTC 2011
>Closed-Date:
>Last-Modified:
>Originator: Mathieu
>Release: 8.2-STABLE
>Organization:
>Environment:
8.2-STABLE FreeBSD 8.2-STABLE #0 r223938M
>Description:
Sometimes, fetch(1) will use 100% CPU time while downloading. There's a loop that will retry I/O syscalls that returned EAGAIN immediately without blocking due to a small bug.
>How-To-Repeat:
Probably only noticeable on slow links.
>Fix:
Index: common.c
===================================================================
--- common.c (revision 223938)
+++ common.c (working copy)
@@ -429,12 +429,6 @@
ssize_t rlen, total;
int r;
- if (fetchTimeout) {
- FD_ZERO(&readfds);
- gettimeofday(&timeout, NULL);
- timeout.tv_sec += fetchTimeout;
- }
-
total = 0;
while (len > 0) {
/*
@@ -474,6 +468,11 @@
return (-1);
}
// assert(rlen == FETCH_READ_WAIT);
+ if (fetchTimeout) {
+ FD_ZERO(&readfds);
+ gettimeofday(&timeout, NULL);
+ timeout.tv_sec += fetchTimeout;
+ }
while (fetchTimeout && !FD_ISSET(conn->sd, &readfds)) {
FD_SET(conn->sd, &readfds);
gettimeofday(&now, NULL);
@@ -576,14 +575,13 @@
ssize_t wlen, total;
int r;
- if (fetchTimeout) {
- FD_ZERO(&writefds);
- gettimeofday(&timeout, NULL);
- timeout.tv_sec += fetchTimeout;
- }
-
total = 0;
while (iovcnt > 0) {
+ if (fetchTimeout) {
+ FD_ZERO(&writefds);
+ gettimeofday(&timeout, NULL);
+ timeout.tv_sec += fetchTimeout;
+ }
while (fetchTimeout && !FD_ISSET(conn->sd, &writefds)) {
FD_SET(conn->sd, &writefds);
gettimeofday(&now, NULL);
>Release-Note:
>Audit-Trail:
>Unformatted:
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