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Miller" , Luc Van Oostenryck , Chris Li , "Paul E. McKenney" , Alexander Potapenko , Arnd Bergmann , Christoph Hellwig , Dmitry Vyukov , Eric Dumazet , Frederic Weisbecker , Greg Kroah-Hartman , Herbert Xu , Ian Rogers , Jann Horn , Joel Fernandes , Johannes Berg , Jonathan Corbet , Josh Triplett , Justin Stitt , Kees Cook , Kentaro Takeda , Lukas Bulwahn , Mark Rutland , Mathieu Desnoyers , Miguel Ojeda , Nathan Chancellor , Neeraj Upadhyay , Nick Desaulniers , Steven Rostedt , Tetsuo Handa , Thomas Gleixner , Thomas Graf , Uladzislau Rezki , Waiman Long , kasan-dev@googlegroups.com, linux-crypto@vger.kernel.org, linux-doc@vger.kernel.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-security-module@vger.kernel.org, linux-sparse@vger.kernel.org, linux-wireless@vger.kernel.org, llvm@lists.linux.dev, rcu@vger.kernel.org References: <20251219154418.3592607-1-elver@google.com> <20251219154418.3592607-16-elver@google.com> Content-Language: en-US From: Bart Van Assche In-Reply-To: <20251219154418.3592607-16-elver@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Stat-Signature: ourixnsotmyf1w37j53pq3u4edg1uo5s X-Rspamd-Queue-Id: F29AD18000C X-Rspam-User: X-HE-Tag: 1769448692-782461 X-HE-Meta: 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 hQFu5Oad zGK0/MtHrVX2BkGtAgOCm7gvDQYLx+d7wURGKOqteHzTbonisaPNugYK9SReM4kfsdja66o7Xa4KYZ648AaXyig86BlNmJtjtW+iuwN78s62E3lYn9V0LV1btxRC3RnxVdh+bhZC6L+VDDRkQwwNV51dZ1cTx28sAg2s3wsALsFs2rnNiDeeyqJMS7P2Gv+4l4r9dRcBJZXf/DYlGIFOOjD0P2kNJKigf82Eaez74qtiBdTC6QBQQxrpY9YJTPyW7rkgG+IDHINrfsM9rNBVNdY5GtkA35WO3c0lffkpFIeo7GfKVU5rg8lQyor4EAS7u1PZLcNb05QfE08Eu69w/7ybqLcuBFGp8wzEJVgkVgd0aTgk= 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: On 12/19/25 7:40 AM, Marco Elver wrote: > +/* > + * No-op helper to denote that ssp must be held. Because SRCU-protected pointers > + * should still be marked with __rcu_guarded, and we do not want to mark them > + * with __guarded_by(ssp) as it would complicate annotations for writers, we > + * choose the following strategy: srcu_dereference_check() calls this helper > + * that checks that the passed ssp is held, and then fake-acquires 'RCU'. > + */ > +static inline void __srcu_read_lock_must_hold(const struct srcu_struct *ssp) __must_hold_shared(ssp) { } > > /** > * srcu_dereference_check - fetch SRCU-protected pointer for later dereferencing > @@ -223,9 +233,15 @@ static inline int srcu_read_lock_held(const struct srcu_struct *ssp) > * to 1. The @c argument will normally be a logical expression containing > * lockdep_is_held() calls. > */ > -#define srcu_dereference_check(p, ssp, c) \ > - __rcu_dereference_check((p), __UNIQUE_ID(rcu), \ > - (c) || srcu_read_lock_held(ssp), __rcu) > +#define srcu_dereference_check(p, ssp, c) \ > +({ \ > + __srcu_read_lock_must_hold(ssp); \ > + __acquire_shared_ctx_lock(RCU); \ > + __auto_type __v = __rcu_dereference_check((p), __UNIQUE_ID(rcu), \ > + (c) || srcu_read_lock_held(ssp), __rcu); \ > + __release_shared_ctx_lock(RCU); \ > + __v; \ > +}) Hi Marco, The above change is something I'm not happy about. The original implementation of the srcu_dereference_check() macro shows that it is sufficient to either hold an SRCU reader lock or the updater lock ('c'). The addition of "__srcu_read_lock_must_hold()" will cause compilation to fail if the caller doesn't hold an SRCU reader lock. I'm concerned that this will either lead to adding __no_context_analysis to SRCU updater code that uses srcu_dereference_check() or to adding misleading __assume_ctx_lock(ssp) annotations in SRCU updater code. Thanks, Bart.