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a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1725606214; h=from:from:reply-to: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=Kv/kFa4PXVn2f7O61rVSDQJ/xaLb2UHmwszpLS8QnfA=; b=f1bER+WEXAHbqjN0ELCRU6jM2RkD75fv+eMSftUwHfOZMs63NnhEYmI28I5DYVorRD1iNr /dM/bjb6/FdsYNvcsLGatmu/ZZmxIu33VabbEV5Ad5QScZBv4GjlJanbcx670O5vkKhfQm ncvUfMlOS2pPeAm2GF4V1xfNtoMGTYs= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1725606214; h=from:from:reply-to: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=Kv/kFa4PXVn2f7O61rVSDQJ/xaLb2UHmwszpLS8QnfA=; b=mmvEPhkZwZsWrTVNfGP43gUrXiMu1axEnamghYNx0Hb2OZukpppdWBa7na1KE1V6YFUoIk 5XeAn+uOB8OBmSBg== Date: Fri, 6 Sep 2024 09:03:34 +0200 (CEST) From: Miroslav Benes To: zhang warden cc: Josh Poimboeuf , Jiri Kosina , Petr Mladek , Joe Lawrence , live-patching@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 1/2] Introduce klp_ops into klp_func structure In-Reply-To: Message-ID: References: <20240828022350.71456-1-zhangwarden@gmail.com> <20240828022350.71456-2-zhangwarden@gmail.com> User-Agent: Alpine 2.21 (LSU 202 2017-01-01) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Spam-Score: -4.30 X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-0.999]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; RCPT_COUNT_SEVEN(0.00)[7]; FREEMAIL_TO(0.00)[gmail.com]; MIME_TRACE(0.00)[0:+]; RCVD_COUNT_ZERO(0.00)[0]; ARC_NA(0.00)[]; MID_RHS_MATCH_FROMTLD(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.cz:email] X-Spam-Flag: NO X-Spam-Level: Hi, On Thu, 5 Sep 2024, zhang warden wrote: > > Hi, Miroslav > > On Sep 5, 2024, at 18:10, Miroslav Benes wrote: > > > > Hi, > > > > the subject is missing "livepatch: " prefix and I would prefer something > > like > > > > "livepatch: Move struct klp_ops to struct klp_func" > > > > On Wed, 28 Aug 2024, Wardenjohn wrote: > > > >> Before introduce feature "using". Klp transition will need an > >> easier way to get klp_ops from klp_func. > > > > I think that the patch might make sense on its own as a > > cleanup/optimization as Petr suggested. If fixed. See below. Then the > > changelog can be restructured and the above can be removed. > > > > After the previous discuss, maybe this patch of "livepatch: Move struct > klp_ops to struct klp_func" is useful, while the second patch need to be > considered later, right? Yes, but keep them in one set for now, please. > >> diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h > >> index 51a258c24ff5..d874aecc817b 100644 > >> --- a/include/linux/livepatch.h > >> +++ b/include/linux/livepatch.h > >> @@ -22,6 +22,25 @@ > >> #define KLP_TRANSITION_UNPATCHED 0 > >> #define KLP_TRANSITION_PATCHED 1 > >> > >> +/** > >> + * struct klp_ops - structure for tracking registered ftrace ops structs > >> + * > >> + * A single ftrace_ops is shared between all enabled replacement functions > >> + * (klp_func structs) which have the same old_func. This allows the switch > >> + * between function versions to happen instantaneously by updating the klp_ops > >> + * struct's func_stack list. The winner is the klp_func at the top of the > >> + * func_stack (front of the list). > >> + * > >> + * @node: node for the global klp_ops list > >> + * @func_stack: list head for the stack of klp_func's (active func is on top) > >> + * @fops: registered ftrace ops struct > >> + */ > >> +struct klp_ops { > >> + struct list_head node; > > > > Not needed anymore. > > What is not needed any more, do you means the comment? node member. You removed the global list, hence this member is not needed anymore. > > > >> + struct list_head func_stack; > >> + struct ftrace_ops fops; > >> +}; > >> + > >> > >> diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c > >> index 52426665eecc..e4572bf34316 100644 > >> --- a/kernel/livepatch/core.c > >> +++ b/kernel/livepatch/core.c > >> @@ -760,6 +760,8 @@ static int klp_init_func(struct klp_object *obj, struct klp_func *func) > >> if (!func->old_name) > >> return -EINVAL; > >> > >> + func->ops = NULL; > >> + > > > > Any reason why it is not added a couple of lines later alongside the rest > > of the initialization? > > Do you mean I should add couple of lines after 'return -EINVAL' ? No, I am asking if there is a reason why you added 'func->ops = NULL;' here and not right after the rest of func initializations INIT_LIST_HEAD(&func->stack_node); func->patched = false; func->transition = false; > > > >> /* > >> * NOPs get the address later. The patched module must be loaded, > >> * see klp_init_object_loaded(). > >> diff --git a/kernel/livepatch/patch.c b/kernel/livepatch/patch.c > >> index 90408500e5a3..8ab9c35570f4 100644 > >> --- a/kernel/livepatch/patch.c > >> +++ b/kernel/livepatch/patch.c > >> @@ -20,18 +20,25 @@ > >> #include "patch.h" > >> #include "transition.h" > >> > >> -static LIST_HEAD(klp_ops); > >> > >> struct klp_ops *klp_find_ops(void *old_func) > >> { > >> - struct klp_ops *ops; > >> + struct klp_patch *patch; > >> + struct klp_object *obj; > >> struct klp_func *func; > >> > >> - list_for_each_entry(ops, &klp_ops, node) { > >> - func = list_first_entry(&ops->func_stack, struct klp_func, > >> - stack_node); > >> - if (func->old_func == old_func) > >> - return ops; > >> + klp_for_each_patch(patch) { > >> + klp_for_each_object(patch, obj) { > >> + klp_for_each_func(obj, func) { > >> + /* > >> + * Ignore entry where func->ops has not been > >> + * assigned yet. It is most likely the one > >> + * which is about to be created/added. > >> + */ > >> + if (func->old_func == old_func && func->ops) > >> + return func->ops; > >> + } > >> + } > >> } > > > > The function is not used anywhere after this patch. > > > > Maybe there still other places will call this klp_find_ops? Is it safe to delete it? If you have no other plans with it, then it can be removed since there is no user after the patch. Miroslav