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Code Releases Activity

RCU Unwinder refactored from route table to a separate structure

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This commit is contained in:
Maria Matejka 2024-05-14 10:46:10 +02:00
parent eaf187b57b
commit 6fb467a54c
5 changed files with 50 additions and 22 deletions
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1
conf/conf.c
View File

@ -40,7 +40,6 @@
* text to make the parser recognize only the rules corresponding to CLI commands.
*/
#include <setjmp.h>
#include <stdarg.h>
#undef LOCAL_DEBUG

1
lib/birdlib.h
View File

@ -10,6 +10,7 @@
#define _BIRD_BIRDLIB_H_
#include <stddef.h>
#include <setjmp.h>
#include "sysdep/config.h"
#include "lib/alloca.h"

40
lib/locking.h
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@ -10,6 +10,7 @@
#define _BIRD_LOCKING_H_
#include "lib/macro.h"
#include "lib/rcu.h"
struct domain_generic;
struct pool;
@ -337,4 +338,43 @@ static inline void locking_unwind(struct lock_order *desired)
#define LOBJ_PRIV(_obj, _level) \
({ ASSERT_DIE(DOMAIN_IS_LOCKED(_level, (_obj)->lock)); &(_obj)->priv; })
/*
* RCU retry unwinder
*
* Start a retriable operation with RCU_ANCHOR() and pass the _i object along
* with the code which may then call RCU_RETRY() to return back to RCU_ANCHOR
* and try again.
*/
struct rcu_unwinder {
struct lock_order locking_stack;
u64 retry;
jmp_buf buf;
};
static inline void _rcu_unwinder_unlock_(struct rcu_unwinder *o UNUSED)
{
rcu_read_unlock();
}
#define RCU_UNWIND_WARN 4096
#define RCU_ANCHOR(_i) \
CLEANUP(_rcu_unwinder_unlock_) struct rcu_unwinder _s##_i = {}; \
struct rcu_unwinder *_i = &_s##_i; \
if (setjmp(_i->buf)) { \
rcu_read_unlock(); \
locking_unwind(&_i->locking_stack); \
birdloop_yield(); \
if (!(++_i->retry % RCU_UNWIND_WARN)) \
log(L_WARN "Suspiciously many RCU_ANCHORs retried (%lu)" \
" at %s:%d", _i->retry, __FILE__, __LINE__); \
} \
_i->locking_stack = locking_stack; \
rcu_read_lock(); \
#define RCU_RETRY(_i) do { if (_i) longjmp(_i->buf, 1); else bug("No rcu retry allowed here"); } while (0)
#define RCU_WONT_RETRY ((struct rcu_unwinder *) NULL)
#endif

29
nest/rt-table.c
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@ -215,9 +215,7 @@ static inline rtable *rt_pub_to_pub(rtable *tab) { return tab; }
*/
struct rtable_reading {
rtable *t;
struct lock_order locking_stack;
u64 retry;
jmp_buf buf;
struct rcu_unwinder *u;
};
static inline void _rt_rcu_unlock_(struct rtable_reading *o)
@ -226,25 +224,17 @@ static inline void _rt_rcu_unlock_(struct rtable_reading *o)
rcu_read_unlock();
}
#define RT_READ(_o, _i) \
CLEANUP(_rt_rcu_unlock_) struct rtable_reading _s##_i = { .t = _o }; \
struct rtable_reading *_i = &_s##_i; \
if (setjmp(_i->buf)) { \
rcu_read_unlock(); \
locking_unwind(&_i->locking_stack); \
birdloop_yield(); \
if (!(++_i->retry % NET_GET_BLOCK_WARN)) \
log(L_WARN "Suspiciously many RT_READs retried (%lu) in table %s" \
" at %s:%d", _i->retry, _i->t->name, __FILE__, __LINE__); \
} \
_i->locking_stack = locking_stack; \
rcu_read_lock(); \
#define RT_READ_ANCHORED(_o, _i, _u) \
struct rtable_reading _s##_i = { .t = _o, .u = _u, }, *_i = &_s##_i;
#define RT_READ_RETRY(tr) do { if (RT_IS_LOCKED(tr->t)) bug("No obsolete route allowed here"); else longjmp(tr->buf, 1); } while (0)
#define RT_READ(_o, _i) RCU_ANCHOR(_u##_i); RT_READ_ANCHORED(_o, _i, _u##_i);
#define RT_READ_RETRY(tr) RCU_RETRY(tr->u)
#define RT_READ_LOCKED(_o, _i) \
struct rtable_reading _s##_i = { .t = RT_PUB(_o) }, \
*_i = ({ ASSERT_DIE(RT_IS_LOCKED(_o)); &_s##_i; }); \
ASSERT_DIE(RT_IS_LOCKED(_o)); \
struct rtable_reading _s##_i = { .t = RT_PUB(_o), .u = RCU_WONT_RETRY, }, *_i = &_s##_i;
#define RTE_IS_OBSOLETE(s) ((s)->rte.flags & REF_OBSOLETE)
#define RTE_OBSOLETE_CHECK(tr, _s) ({ \
@ -253,7 +243,6 @@ static inline void _rt_rcu_unlock_(struct rtable_reading *o)
RT_READ_RETRY(tr); \
s; })
#define NET_GET_BLOCK_WARN 16384
#define NET_READ_WALK_ROUTES(tr, n, ptr, r) \
for (struct rte_storage *r, * _Atomic *ptr = &(n)->routes; \
r = RTE_OBSOLETE_CHECK(tr, atomic_load_explicit(ptr, memory_order_acquire)); \

1
proto/bgp/bgp.h
View File

@ -12,7 +12,6 @@
#define _BIRD_BGP_H_
#include <stdint.h>
#include <setjmp.h>
#include "nest/bird.h"
#include "nest/route.h"
#include "nest/bfd.h"