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| author | Paolo Bonzini <pbonzini@redhat.com> | 2015-01-13 17:34:15 +0100 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2015-02-02 16:55:10 +0100 |
| commit | d62cb4f2fdc0977f9ca9f41d297c3d2c44874171 (patch) | |
| tree | cad4b85fa5ddff699506743187e746e5e456231c | |
| parent | 8fda74a52bf3fa63cb80c877b6946cb9143f96cc (diff) | |
| download | hqemu-d62cb4f2fdc0977f9ca9f41d297c3d2c44874171.zip hqemu-d62cb4f2fdc0977f9ca9f41d297c3d2c44874171.tar.gz | |
rcu: allow nesting of rcu_read_lock/rcu_read_unlock
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | include/qemu/rcu.h | 15 | ||||
| -rw-r--r-- | tests/rcutorture.c | 2 |
2 files changed, 16 insertions, 1 deletions
diff --git a/include/qemu/rcu.h b/include/qemu/rcu.h index cfef36e..da043f2 100644 --- a/include/qemu/rcu.h +++ b/include/qemu/rcu.h @@ -68,6 +68,9 @@ struct rcu_reader_data { unsigned long ctr; bool waiting; + /* Data used by reader only */ + unsigned depth; + /* Data used for registry, protected by rcu_gp_lock */ QLIST_ENTRY(rcu_reader_data) node; }; @@ -77,8 +80,13 @@ extern __thread struct rcu_reader_data rcu_reader; static inline void rcu_read_lock(void) { struct rcu_reader_data *p_rcu_reader = &rcu_reader; + unsigned ctr; + + if (p_rcu_reader->depth++ > 0) { + return; + } - unsigned ctr = atomic_read(&rcu_gp_ctr); + ctr = atomic_read(&rcu_gp_ctr); atomic_xchg(&p_rcu_reader->ctr, ctr); if (atomic_read(&p_rcu_reader->waiting)) { atomic_set(&p_rcu_reader->waiting, false); @@ -90,6 +98,11 @@ static inline void rcu_read_unlock(void) { struct rcu_reader_data *p_rcu_reader = &rcu_reader; + assert(p_rcu_reader->depth != 0); + if (--p_rcu_reader->depth > 0) { + return; + } + atomic_xchg(&p_rcu_reader->ctr, 0); if (atomic_read(&p_rcu_reader->waiting)) { atomic_set(&p_rcu_reader->waiting, false); diff --git a/tests/rcutorture.c b/tests/rcutorture.c index cb78411..60a2ccf 100644 --- a/tests/rcutorture.c +++ b/tests/rcutorture.c @@ -255,9 +255,11 @@ static void *rcu_read_stress_test(void *arg) if (p->mbtest == 0) { n_mberror++; } + rcu_read_lock(); for (i = 0; i < 100; i++) { garbage++; } + rcu_read_unlock(); pc = p->pipe_count; rcu_read_unlock(); if ((pc > RCU_STRESS_PIPE_LEN) || (pc < 0)) { |
