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Wed, 27 May 2026 19:16:16 +0000 Message-ID: Date: Wed, 27 May 2026 21:16:16 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/2] [gdb/symtab] Fix data race in try_open_dwop_file To: Tom Tromey Cc: gdb-patches@sourceware.org References: <20260216180925.3174052-1-tdevries@suse.de> <20260216180925.3174052-3-tdevries@suse.de> <877brrnxrw.fsf@tromey.com> Content-Language: en-US From: Tom de Vries In-Reply-To: <877brrnxrw.fsf@tromey.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Queue-Id: 132CC6A9D8 X-Rspamd-Action: no action X-Spamd-Result: default: False [-4.51 / 50.00]; BAYES_HAM(-3.00)[99.99%]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; RCPT_COUNT_TWO(0.00)[2]; FUZZY_RATELIMITED(0.00)[rspamd.com]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; RCVD_TLS_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; DNSWL_BLOCKED(0.00)[2a07:de40:b281:104:10:150:64:97:from,2a07:de40:b281:106:10:150:64:167:received]; RCVD_VIA_SMTP_AUTH(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; DKIM_TRACE(0.00)[suse.de:+]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:email, suse.de:dkim, suse.de:mid, sourceware.org:url, imap1.dmz-prg2.suse.org:rdns, imap1.dmz-prg2.suse.org:helo] X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: gdb-patches-bounces~public-inbox=simark.ca@sourceware.org On 3/4/26 9:29 PM, Tom Tromey wrote: >>>>>> "Tom" == Tom de Vries writes: > > Tom> The call to bfd_check_format in try_open_dwop_file: > Tom> ... > Tom> /* The operations below are not thread-safe, use a lock to synchronize > Tom> concurrent accesses. */ > Tom> static gdb::mutex mutex; > Tom> gdb::lock_guard lock (mutex); > > Tom> if (!bfd_check_format (sym_bfd.get (), bfd_object)) > Tom> return NULL; > Tom> ... > Tom> accesses the sym_bfd.get () BFD, so it should be guarded by the global BFD > Tom> lock. > > Doesn't bfd_check_format do this itself? Hi Tom, thanks for the review, and sorry for the delay in replying, I seem to have dropped the ball on this. AFAIU, bfd_check_format does locking, but it's only used to [1]: ... lock the internal global data structures of BFD (like its global cache or some global counter), but not data in individual `bfd *`instances. ... So while it does do locking, it's not sufficient. > Otherwise, don't we need to wrap all calls to bfd_check_format? > Agreed, and likewise for bfd_check_format_matches. I've submitted a v3 that adds this ( https://sourceware.org/pipermail/gdb-patches/2026-May/227652.html ). Thanks, - Tom > Tom> The local lock also guarded a call to gdb_bfd_record_inclusion, which doesn't > Tom> do any locking, so likewise use the global BFD lock in > Tom> gdb_bfd_record_inclusion. > > This part seems unobjectionable to me. > > Tom [1] https://sourceware.org/pipermail/gdb-patches/2026-January/224291.html