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Revert "BUG/MEDIUM: lists: Lock the element while we check if it is in a list."

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This reverts previous commit 347bbf79d20e1cff57075a8a378355dfac2475e2i.

The original code was correct. This patch resulted from a mistaken analysis
and breaks the scheduler:

 ########################## Starting vtest ##########################
 Testing with haproxy version: 2.2-dev11-90b7d9-23
 #    top  TEST reg-tests/lua/close_wait_lf.vtc TIMED OUT (kill -9)
 #    top  TEST reg-tests/lua/close_wait_lf.vtc FAILED (10.008) signal=9
 1 tests failed, 0 tests skipped, 88 tests passed

 Program terminated with signal SIGABRT, Aborted.
 [Current thread is 1 (Thread 0x7fb0dac2c700 (LWP 11292))]
 (gdb) bt
 #0  0x00007fb0e7c143f8 in raise () from /lib64/libc.so.6
 #1  0x00007fb0e7c15ffa in abort () from /lib64/libc.so.6
 #2  0x000000000053f5d6 in ha_panic () at src/debug.c:269
 #3  0x00000000005a6248 in wdt_handler (sig=14, si=<optimized out>, arg=<optimized out>) at src/wdt.c:119
 #4  <signal handler called>
 #5  0x00000000004fbccd in tasklet_wakeup (tl=0x1b5abc0) at include/haproxy/task.h:351
 #6  listener_accept (fd=<optimized out>) at src/listener.c:999
 #7  0x00000000004262df in fd_update_events (evts=<optimized out>, fd=6) at include/haproxy/fd.h:418
 #8  _do_poll (p=<optimized out>, exp=<optimized out>, wake=<optimized out>) at src/ev_epoll.c:251
 #9  0x0000000000548d0f in run_poll_loop () at src/haproxy.c:2949
 #10 0x000000000054908b in run_thread_poll_loop (data=<optimized out>) at src/haproxy.c:3067
 #11 0x00007fb0e902b684 in start_thread () from /lib64/libpthread.so.0
 #12 0x00007fb0e7ce5eed in clone () from /lib64/libc.so.6
 (gdb) up
 #5  0x00000000004fbccd in tasklet_wakeup (tl=0x1b5abc0) at include/haproxy/task.h:351
 351                     if (MT_LIST_ADDQ(&task_per_thread[tl->tid].shared_tasklet_list, (struct mt_list *)&tl->list) == 1) {

If the commit above is ever backported, this one must be as well!
This commit is contained in:
Willy Tarreau 2020-06-29 21:37:57 +02:00
parent 347bbf79d2
commit d59946e673
1 changed files with 6 additions and 34 deletions
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40
include/haproxy/list.h
View File

@ -230,8 +230,8 @@
int _ret = 0; \
struct mt_list *lh = (_lh), *el = (_el); \
while (1) { \
struct mt_list *n, *n2; \
struct mt_list *p, *p2; \
struct mt_list *n; \
struct mt_list *p; \
n = _HA_ATOMIC_XCHG(&(lh)->next, MT_LIST_BUSY); \
if (n == MT_LIST_BUSY) \
continue; \
@ -241,23 +241,9 @@
__ha_barrier_store(); \
continue; \
} \
n2 = _HA_ATOMIC_XCHG(&(el)->next, MT_LIST_BUSY); \
if (n2 != (el)) { \
if ((el)->next != (el) || (el)->prev != (el)) { \
(n)->prev = p; \
(lh)->next = n; \
(el)->next = n2; \
if (n2 == MT_LIST_BUSY) \
continue; \
break; \
} \
p2 = _HA_ATOMIC_XCHG(&(el)->prev, MT_LIST_BUSY); \
if (p2 != (el)) { \
n->prev = p; \
(lh)->next = n; \
(el)->next = n2; \
(el)->prev = p2; \
if (p2 == MT_LIST_BUSY) \
continue; \
break; \
} \
(el)->next = n; \
@ -283,8 +269,8 @@
int _ret = 0; \
struct mt_list *lh = (_lh), *el = (_el); \
while (1) { \
struct mt_list *n, *n2; \
struct mt_list *p, *p2; \
struct mt_list *n; \
struct mt_list *p; \
p = _HA_ATOMIC_XCHG(&(lh)->prev, MT_LIST_BUSY); \
if (p == MT_LIST_BUSY) \
continue; \
@ -294,23 +280,9 @@
__ha_barrier_store(); \
continue; \
} \
n2 = _HA_ATOMIC_XCHG(&(el)->next, MT_LIST_BUSY); \
if (n2 != (el)) { \
if ((el)->next != (el) || (el)->prev != (el)) { \
p->next = n; \
(lh)->prev = p; \
(el)->next = n2; \
if (n2 == MT_LIST_BUSY) \
continue; \
break; \
} \
p2 = _HA_ATOMIC_XCHG(&(el)->prev, MT_LIST_BUSY); \
if (p2 != (el)) { \
p->next = n; \
(lh)->prev = p; \
(el)->next = n2; \
(el)->prev = p2; \
if (p2 == MT_LIST_BUSY) \
continue; \
break; \
} \
(el)->next = n; \