From: Mateusz Guzik <mjguzik@gmail.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: bpf@vger.kernel.org, andrii@kernel.org, memxor@gmail.com,
akpm@linux-foundation.org, peterz@infradead.org, vbabka@suse.cz,
bigeasy@linutronix.de, rostedt@goodmis.org, houtao1@huawei.com,
hannes@cmpxchg.org, shakeel.butt@linux.dev, mhocko@suse.com,
willy@infradead.org, tglx@linutronix.de, jannh@google.com,
tj@kernel.org, linux-mm@kvack.org, kernel-team@fb.com
Subject: Re: [PATCH bpf-next v9 1/6] locking/local_lock: Introduce localtry_lock_t
Date: Tue, 11 Mar 2025 16:44:30 +0100 [thread overview]
Message-ID: <oswrb2f2mx36l6f624hqjvx4lkjdi26xwfwux2wi2mlzmdmmf2@dpaodu372ldv> (raw)
In-Reply-To: <20250222024427.30294-2-alexei.starovoitov@gmail.com>
On Fri, Feb 21, 2025 at 06:44:22PM -0800, Alexei Starovoitov wrote:
> +#define __localtry_lock(lock) \
> + do { \
> + localtry_lock_t *lt; \
> + preempt_disable(); \
> + lt = this_cpu_ptr(lock); \
> + local_lock_acquire(<->llock); \
> + WRITE_ONCE(lt->acquired, 1); \
> + } while (0)
I think these need compiler barriers.
I checked with gcc docs (https://gcc.gnu.org/onlinedocs/gcc/Volatiles.html)
and found this as confirmation:
> Accesses to non-volatile objects are not ordered with respect to volatile accesses.
Unless the Linux kernel is built with some magic to render this moot(?).
next prev parent reply other threads:[~2025-03-11 15:44 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-22 2:44 [PATCH bpf-next v9 0/6] bpf, mm: Introduce try_alloc_pages() Alexei Starovoitov
2025-02-22 2:44 ` [PATCH bpf-next v9 1/6] locking/local_lock: Introduce localtry_lock_t Alexei Starovoitov
2025-03-11 15:44 ` Mateusz Guzik [this message]
2025-03-11 16:20 ` Sebastian Andrzej Siewior
2025-03-11 16:31 ` Mateusz Guzik
2025-03-11 20:21 ` Vlastimil Babka
2025-03-11 22:24 ` Alexei Starovoitov
2025-03-12 8:29 ` Vlastimil Babka
2025-03-14 21:05 ` Alexei Starovoitov
2025-03-14 21:08 ` Vlastimil Babka
2025-03-14 21:18 ` Alexei Starovoitov
2025-02-22 2:44 ` [PATCH bpf-next v9 2/6] mm, bpf: Introduce try_alloc_pages() for opportunistic page allocation Alexei Starovoitov
2025-03-11 2:04 ` Andrew Morton
2025-03-11 13:32 ` Alexei Starovoitov
2025-03-11 18:04 ` Mateusz Guzik
2025-03-12 9:45 ` Steven Rostedt
2025-03-15 0:34 ` Alexei Starovoitov
2025-03-12 10:00 ` Vlastimil Babka
2025-03-12 19:06 ` Shakeel Butt
2025-03-13 8:44 ` Michal Hocko
2025-03-13 14:21 ` Vlastimil Babka
2025-03-13 16:02 ` Shakeel Butt
2025-03-14 10:16 ` Michal Hocko
2025-03-15 0:51 ` Alexei Starovoitov
2025-02-22 2:44 ` [PATCH bpf-next v9 3/6] mm, bpf: Introduce free_pages_nolock() Alexei Starovoitov
2025-02-22 2:44 ` [PATCH bpf-next v9 4/6] memcg: Use trylock to access memcg stock_lock Alexei Starovoitov
2025-02-22 2:44 ` [PATCH bpf-next v9 5/6] mm, bpf: Use memcg in try_alloc_pages() Alexei Starovoitov
2025-02-22 2:44 ` [PATCH bpf-next v9 6/6] bpf: Use try_alloc_pages() to allocate pages for bpf needs Alexei Starovoitov
2025-02-26 3:19 ` [PATCH bpf-next v9 0/6] bpf, mm: Introduce try_alloc_pages() Alexei Starovoitov
2025-02-27 17:50 ` patchwork-bot+netdevbpf
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