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Hermes SMTP Server) with ESMTPA ID c4fb2a7615a55ae053737767c3fd14bf; Tue, 20 May 2025 05:51:22 +0000 (UTC) From: Mark Millard Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit List-Id: Discussions about the use of FreeBSD-current List-Archive: https://lists.freebsd.org/archives/freebsd-current List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-current@FreeBSD.org Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3826.600.51.1.1\)) Subject: RE: Just a question about sys/kern/subr_witness.c where witness_watch may be flipped to -1 Message-Id: <2950BB1C-6672-4110-8485-3CB9ED0DAEC8@yahoo.com> Date: Mon, 19 May 2025 22:51:12 -0700 To: Dennis Clarke , FreeBSD Current X-Mailer: Apple Mail (2.3826.600.51.1.1) References: <2950BB1C-6672-4110-8485-3CB9ED0DAEC8.ref@yahoo.com> X-Rspamd-Queue-Id: 4b1kFX2T7zz3YP1 X-Spamd-Bar: --- X-Spamd-Result: default: False [-3.50 / 15.00]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-1.00)[-0.999]; MV_CASE(0.50)[]; DMARC_POLICY_ALLOW(-0.50)[yahoo.com,reject]; R_SPF_ALLOW(-0.20)[+ptr:yahoo.com]; R_DKIM_ALLOW(-0.20)[yahoo.com:s=s2048]; MIME_GOOD(-0.10)[text/plain]; RCVD_TLS_LAST(0.00)[]; TO_DN_ALL(0.00)[]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; RCPT_COUNT_TWO(0.00)[2]; FREEMAIL_ENVFROM(0.00)[yahoo.com]; FREEMAIL_FROM(0.00)[yahoo.com]; FROM_HAS_DN(0.00)[]; ASN(0.00)[asn:36647, ipnet:98.137.64.0/20, country:US]; DWL_DNSWL_NONE(0.00)[yahoo.com:dkim]; TO_MATCH_ENVRCPT_SOME(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; DKIM_TRACE(0.00)[yahoo.com:+]; MLMMJ_DEST(0.00)[freebsd-current@freebsd.org]; RWL_MAILSPIKE_POSSIBLE(0.00)[98.137.64.204:from]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCVD_IN_DNSWL_NONE(0.00)[98.137.64.204:from] Dennis Clarke wrote on Date: Tue, 20 May 2025 02:33:58 UTC: > Just an odd message to see on the console : > > # witness_lock_list_get: witness exhausted > > Looking at https://cgit.freebsd.org/src/tree/sys/kern/subr_witness.c it > seems that the comment at line 370 is very clear : > > /* > * If set to 0, lock order checking is disabled. If set to -1, > * witness is completely disabled. Otherwise witness performs full > * lock order checking for all locks. At runtime, lock order checking > * may be toggled. However, witness cannot be reenabled once it is > * completely disabled. > */ > static int witness_watch = 1; > > So I wonder how I managed to get that message "witness exhausted" ? > > At line 2203 I see : > > static struct lock_list_entry * > witness_lock_list_get(void) > { > struct lock_list_entry *lle; > > if (witness_watch == -1) > return (NULL); > mtx_lock_spin(&w_mtx); > lle = w_lock_list_free; > if (lle == NULL) { Looks to me like "out of required resources, cannot continue with the mode of use" code: an empty free list so no node is available to put to use to continue with the witness handling. > witness_watch = -1; > mtx_unlock_spin(&w_mtx); > printf("%s: witness exhausted\n", __func__); > return (NULL); > } > w_lock_list_free = lle->ll_next; > mtx_unlock_spin(&w_mtx); > bzero(lle, sizeof(*lle)); > return (lle); > } > > Where it seems that indeed witness_watch has been flipped to -1 and that > functionality is now gone? Until the next boot, anyway. === Mark Millard marklmi at yahoo.com