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bh=ZYgRJSbyD7/Hp5o7tmaedYa+68K/cZrZ3MIJ9Qms0rk=; b=s80nneN0RJnjEWzztjYB9n4H8XXU9fkWNo+MbJptBlKOoO0LfBNAPXwrH9GSYK0tLFmvaW v81B+E8o/KyD3ZDQ== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id 21F0113782; Mon, 29 Sep 2025 07:16:48 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id iUTxB2Ay2mh+GAAAD6G6ig (envelope-from ); Mon, 29 Sep 2025 07:16:48 +0000 Message-ID: Date: Mon, 29 Sep 2025 09:16:47 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] locking/local_lock: s/l/__l/ and s/tl/__tl/ to reduce risk of shadowing Content-Language: en-US To: Vincent Mailhol , Shakeel Butt , Sebastian Andrzej Siewior , Alexei Starovoitov , Andrew Morton , Peter Zijlstra , Ingo Molnar , Will Deacon , Waiman Long , Boqun Feng Cc: linux-kernel@vger.kernel.org References: <20250925-local_lock_internal_fix_shadow-v2-1-d3b85ee775a4@kernel.org> <6c49739d-6f2a-4c49-a04b-9774f10a6925@suse.cz> <5f7821d5-0b48-4600-ab99-d76a52361fc1@kernel.org> From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; 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charset=UTF-8 Content-Transfer-Encoding: 8bit X-Spamd-Result: default: False [-3.01 / 50.00]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; MIME_TRACE(0.00)[0:+]; FREEMAIL_TO(0.00)[kernel.org,linux.dev,linutronix.de,linux-foundation.org,infradead.org,redhat.com,gmail.com]; FUZZY_RATELIMITED(0.00)[rspamd.com]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; ARC_NA(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; DKIM_TRACE(0.00)[suse.cz:+]; TO_DN_SOME(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; RCVD_TLS_ALL(0.00)[]; DNSWL_BLOCKED(0.00)[2a07:de40:b281:106:10:150:64:167:received,2a07:de40:b281:104:10:150:64:97:from]; RCPT_COUNT_SEVEN(0.00)[11]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; TAGGED_RCPT(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.cz:mid,suse.cz:dkim,imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns] X-Spam-Flag: NO X-Spam-Level: X-Rspamd-Queue-Id: 393CA2F790 X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Action: no action X-Spam-Score: -3.01 On 9/27/25 05:04, Vincent Mailhol wrote: > On 9/26/25 11:16 PM, Vlastimil Babka wrote: >> +CC LOCKING PRIMITIVES maintainers. Looks like local_lock files were never >> added to the section, should we? >> >> On 9/24/25 20:03, Vincent Mailhol wrote: >>> The Linux kernel coding style [1] advises to avoid common variable >>> names in function-like macros to reduce the risk of collisions. >> >> I think it would be better if the tools like sparse could recognize if the >> shadowing happens inside a macro only and thus really unlikely to cause a >> misuse due to confusion (code thinks it's manipulating an outer instance but >> instead it's the inner one), because macros in their definition would never >> intend to manipulate a possible outer instance, right? Or are there any >> other problems due to shadowing besides this risk? > > Thank would mean: > > - rewriting the shadowing check in sparse > - removing the -Wshadow from the W=2 list > - modifying the kernel coding style > > I am not against this. But I am not unhappy with the current status quo either. > > So far, I kept sending patches whenever I saw such shadow warning in header > files. And over the last five years, this resulted in only three occurrences: > > - commit 146034fed6ee ("x86/asm/bitops: Use __builtin_ffs() to evaluate > constant expressions") > Link: https://git.kernel.org/torvalds/c/146034fed6ee > > > - commit 9ce02f0fc683 ("x86/bug: Prevent shadowing in __WARN_FLAGS") > Link: https://git.kernel.org/torvalds/c/9ce02f0fc683 > > - this patch > > Between sending one patch every couple year or enrolling to a quest to modify > the tooling, my choice is already made. If someone else want to do this change, > I would be supportive, but that person will not be me. Thanks for that perspective, with that it seems now clear to me that a rare fixup of some macro is indeed much easier. > On a side note, I want to highlight that it is not that I am reluctant to modify > the tooling. For example, I sent contributed this commit to sparse last week: > > commit 366ad4b2fa3e ("Warn about "unsigned value that used to be signed against > zero"") > > Link: > https://git.kernel.org/pub/scm/devel/sparse/sparse-dev.git/commit/?id=366ad4b2fa3e