diff options
| -rw-r--r-- | docs/devel/rcu.txt | 16 | ||||
| -rw-r--r-- | include/qemu/rcu.h | 25 |
2 files changed, 41 insertions, 0 deletions
diff --git a/docs/devel/rcu.txt b/docs/devel/rcu.txt index c84e7f42b2..d83fed2f79 100644 --- a/docs/devel/rcu.txt +++ b/docs/devel/rcu.txt @@ -187,6 +187,22 @@ The following APIs must be used before RCU is used in a thread: Note that these APIs are relatively heavyweight, and should _not_ be nested. +Convenience macros +================== + +Two macros are provided that automatically release the read lock at the +end of the scope. + + RCU_READ_LOCK_GUARD() + + Takes the lock and will release it at the end of the block it's + used in. + + WITH_RCU_READ_LOCK_GUARD() { code } + + Is used at the head of a block to protect the code within the block. + +Note that 'goto'ing out of the guarded block will also drop the lock. DIFFERENCES WITH LINUX ====================== diff --git a/include/qemu/rcu.h b/include/qemu/rcu.h index 22876d1428..9c82683e37 100644 --- a/include/qemu/rcu.h +++ b/include/qemu/rcu.h @@ -154,6 +154,31 @@ extern void call_rcu1(struct rcu_head *head, RCUCBFunc *func); }), \ (RCUCBFunc *)g_free); +typedef void RCUReadAuto; +static inline RCUReadAuto *rcu_read_auto_lock(void) +{ + rcu_read_lock(); + /* Anything non-NULL causes the cleanup function to be called */ + return (void *)(uintptr_t)0x1; +} + +static inline void rcu_read_auto_unlock(RCUReadAuto *r) +{ + rcu_read_unlock(); +} + +G_DEFINE_AUTOPTR_CLEANUP_FUNC(RCUReadAuto, rcu_read_auto_unlock) + +#define WITH_RCU_READ_LOCK_GUARD() \ + WITH_RCU_READ_LOCK_GUARD_(_rcu_read_auto##__COUNTER__) + +#define WITH_RCU_READ_LOCK_GUARD_(var) \ + for (g_autoptr(RCUReadAuto) var = rcu_read_auto_lock(); \ + (var); rcu_read_auto_unlock(var), (var) = NULL) + +#define RCU_READ_LOCK_GUARD() \ + g_autoptr(RCUReadAuto) _rcu_read_auto __attribute__((unused)) = rcu_read_auto_lock() + #ifdef __cplusplus } #endif |