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bh=oCZy9PHIwaJxdVUqA4bjRvSlHrCD3VPWXgi6d8HRy84=; b=ZBDHxZq4UWJwAkXHVqYoOKe5RdE5P6K0bCr7EQS7yi6AlS6JqkdxIU1lyguem5kCZfdGTO otYJiUly1G8RkaoybczWigqswVuWnh/xlSoX9w9sUT6EHzEsChdCjFxgpFRMz4Fl4L7ko9 IghkuICUQ3YNtMRi3/8DnkveEU7gVK2y/RKDQ6Q+Akmzgb+6okIj+DBqhL37ydwMharZha KE3qVwrOUaaqVPmAVQzC+O8Zdf34yz5OcM0BGz2bJDlRRdnuY4aUsWelQTCqEKRbK94KWd axtbHKQBWyrivhna9NI2u933vL5pcmTs6h6/+3tEoOQ21lZxJFEfEMqbX9Q+iQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1719180817; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=oCZy9PHIwaJxdVUqA4bjRvSlHrCD3VPWXgi6d8HRy84=; b=gMWDS26G3xyhqDiLmYwVGq9nj/4yQpFI7Mvc0wCBa2aDhbUlPGq6X/77X64enm26GAnpka Qc9sJ+0YzwoG0PBQ== To: Kent Overstreet , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Jens Axboe , Kent Overstreet , brauner@kernel.org, viro@zeniv.linux.org.uk, Bernd Schubert , linux-mm@kvack.org, Josef Bacik Subject: Re: [PATCH 3/5] fs: sys_ringbuffer In-Reply-To: <20240603003306.2030491-4-kent.overstreet@linux.dev> References: <20240603003306.2030491-1-kent.overstreet@linux.dev> <20240603003306.2030491-4-kent.overstreet@linux.dev> Date: Mon, 24 Jun 2024 00:13:36 +0200 Message-ID: <87frt39ujz.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: E4A40140014 X-Stat-Signature: rx6dujd1whqd8bx6dqb6n9yo3hqpff5i X-HE-Tag: 1719180819-139122 X-HE-Meta: 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 PG/YrB83 CHUBJvOodMDoCaViFGYiM+BIIcOoV3i9dEpA2M/L6/asuVLYJeMIpxVy39WlN4+v7kHlltqCnUPmkKbChKwARCUDHtVMx/5ry06nzki/CU+a2FHcFcVAAJnoRR848PZdD647TsbF6qDgioj4R1QIqkJMhMgnQQEhfFUE4GFuM0QQ+cZR4/KJ/0tL8n4NEwQ/it3U7gHtd/XNsFLY= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Kent! On Sun, Jun 02 2024 at 20:33, Kent Overstreet wrote: > +/* > + * ringbuffer_ptrs - head and tail pointers for a ringbuffer, mappped to > + * userspace: > + */ > +struct ringbuffer_ptrs { The naming is confusing. ringbuffer_ctrl or something like that would be more clear because it's more than just the pointers, which are in fact positions. You have size, mask ... too, no? > + /* > + * We use u32s because this type is shared between the kernel and > + * userspace - ulong/size_t won't work here, we might be 32bit userland > + * and 64 bit kernel, and u64 would be preferable (reduced probability > + * of ABA) but not all architectures can atomically read/write to a u64; > + * we need to avoid torn reads/writes. union rbmagic { u64 __val64; struct { // TOOTIRED: Add big/little endian voodoo u32 __val32; u32 __unused; }; }; Plus a bunch of accessors which depend on BITS_PER_LONG, no? Thanks, tglx