From: Alan Huang <mmpgouride@gmail.com>
To: paulmck@kernel.org, akiyks@gmail.com
Cc: perfbook@vger.kernel.org, Alan Huang <mmpgouride@gmail.com>
Subject: [PATCH v2] CodeSamples/defer: Fix hazard torture
Date: Sat, 22 Apr 2023 10:34:21 +0000 [thread overview]
Message-ID: <20230422103421.1382-1-mmpgouride@gmail.com> (raw)
Because hp_try_record() must check for concurrent modifications,
we should not dereference the pointer. The arg of hazptr_read_stress_test
is always NULL, which is designated at time when create the thread,
therefore, all threads will store their hazard pointer in the same slot.
Also, hazptr_thread_exit will clear their own hazard pointer from
smp_thread_id() * K.
Signed-off-by: Alan Huang <mmpgouride@gmail.com>
---
CodeSamples/defer/hazptr.h | 2 +-
CodeSamples/defer/hazptrtorture.h | 5 ++---
2 files changed, 3 insertions(+), 4 deletions(-)
diff --git a/CodeSamples/defer/hazptr.h b/CodeSamples/defer/hazptr.h
index 759ab53d..e061303d 100644
--- a/CodeSamples/defer/hazptr.h
+++ b/CodeSamples/defer/hazptr.h
@@ -87,7 +87,7 @@ static inline void *hp_record(void **p, //\lnlbl{hr:b}
void *tmp;
do {
- tmp = hp_try_record(*p, hp);
+ tmp = hp_try_record(p, hp);
} while (tmp == (void *)HAZPTR_POISON);
return tmp;
} //\lnlbl{hr:e}
diff --git a/CodeSamples/defer/hazptrtorture.h b/CodeSamples/defer/hazptrtorture.h
index 53efa259..acdd532b 100644
--- a/CodeSamples/defer/hazptrtorture.h
+++ b/CodeSamples/defer/hazptrtorture.h
@@ -99,7 +99,7 @@ void *hazptr_read_perf_test(void *arg)
{
int i;
int me = (long)arg;
- int base = me * K;
+ int base = smp_thread_id() * K;
long long n_reads_local = 0;
hazptr_head_t hh;
hazptr_head_t *hhp = &hh;
@@ -241,8 +241,7 @@ DEFINE_PER_THREAD(long long [HAZPTR_STRESS_PIPE_LEN + 1], hazptr_stress_count);
void *hazptr_read_stress_test(void *arg)
{
- int me = (int)(long)arg;
- int base = me * K;
+ int base = smp_thread_id() * K;
struct hazptr_stress *p;
int pc;
--
2.34.1
next reply other threads:[~2023-04-22 10:34 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-22 10:34 Alan Huang [this message]
2023-04-22 10:39 ` [PATCH v2] CodeSamples/defer: Fix hazard torture Alan Huang
2023-04-22 11:56 ` Akira Yokosawa
2023-04-24 15:44 ` Paul E. McKenney
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