From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from picard.linux.it (picard.linux.it [213.254.12.146]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 199B5C6FD1F for ; Thu, 16 Mar 2023 11:44:27 +0000 (UTC) Received: from picard.linux.it (localhost [IPv6:::1]) by picard.linux.it (Postfix) with ESMTP id B096B3CE5E7 for ; Thu, 16 Mar 2023 12:44:24 +0100 (CET) Received: from in-5.smtp.seeweb.it (in-5.smtp.seeweb.it [217.194.8.5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-384)) (No client certificate requested) by picard.linux.it (Postfix) with ESMTPS id 09C773CB67C for ; Thu, 16 Mar 2023 12:44:13 +0100 (CET) Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by in-5.smtp.seeweb.it (Postfix) with ESMTPS id 1D0E06005D0 for ; Thu, 16 Mar 2023 12:44:12 +0100 (CET) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 5919D1FE01; Thu, 16 Mar 2023 11:44:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1678967052; h=from:from:reply-to: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=K8IYtVCFH3d7AFnr0/2yy7KVbaEOgkT8A6bZDe5sh3k=; b=Wl7L45PL1NiEv2I4l82PSvdWw5jxVQx4B8hJLLvvUBcwMJGtIr8zURVM5UKWnsQWoFnXCq jM4NldLhfH5o9smSZpjZoDPnGtJuusqv428oCIJuILlhcbWNfZyq5MNme2imne1QbCz5hc ERjU9tV5P4Wnc5ar5oFYDve62R0gjxU= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1678967052; h=from:from:reply-to: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=K8IYtVCFH3d7AFnr0/2yy7KVbaEOgkT8A6bZDe5sh3k=; b=PojHjhVessucJiBe4UOYxwuK4RgZbNRT/Aqy5y6KrpRkJq77lToPzEHU1WRoKm0Fi6ixBG 1R+7LZB0TBBtaiAQ== Received: from g78 (unknown [10.163.28.198]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 5DD802C141; Thu, 16 Mar 2023 11:44:11 +0000 (UTC) References: <20230306235715.29868-1-wegao@suse.com> <20230307085139.3574-1-wegao@suse.com> <87ttyo6g7o.fsf@suse.de> <20230315125532.GB10248@localhost> User-agent: mu4e 1.8.13; emacs 28.2 From: Richard Palethorpe To: Wei Gao Date: Thu, 16 Mar 2023 11:10:07 +0000 Organization: Linux Private Site In-reply-to: <20230315125532.GB10248@localhost> Message-ID: <87jzzg3oqg.fsf@suse.de> MIME-Version: 1.0 X-Virus-Scanned: clamav-milter 0.102.4 at in-5.smtp.seeweb.it X-Virus-Status: Clean Subject: Re: [LTP] [PATCH v5] kill01: New case cgroup kill X-BeenThere: ltp@lists.linux.it X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux Test Project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: rpalethorpe@suse.de Cc: Li Wang , ltp@lists.linux.it Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ltp-bounces+ltp=archiver.kernel.org@lists.linux.it Sender: "ltp" Wei Gao writes: > On Mon, Mar 13, 2023 at 10:45:12AM +0000, Richard Palethorpe wrote: >> Hello, >> >> > +static int wait_for_pid(pid_t pid) >> > +{ >> > + int status, ret; >> > + >> > +again: >> > + ret = waitpid(pid, &status, 0); >> > + if (ret == -1) { >> > + if (errno == EINTR) >> > + goto again; >> > + >> > + return -1; >> > + } >> > + >> > + if (!WIFEXITED(status)) >> > + return -1; >> > + >> > + return WEXITSTATUS(status); >> > +} >> >> We have tst_reap_children for this, but this just appears to be wrong >> for this test. > tst_reap_children can not return reason of status, such as i need call > WIFSIGNALED(wstatus) in next patch to make sure children is killed by > signal. > >> > + * A simple process running in a sleep loop until being >> > + * re-parented. >> > + */ >> > +static void child_fn(void) >> > +{ >> > + int ppid = getppid(); >> > + >> > + while (getppid() == ppid) >> > + usleep(1000); >> > + >> > +} >> > + >> > +static int cg_run_nowait(const struct tst_cg_group *const cg, >> > + void (*fn)(void)) >> >> Why keep this function? >> >> If you want to convert tests to LTP, then don't do the minimum possible >> to use the LTP API. Use as much of it as possible otherwise we are just >> importing brittle self tests. >> > function is useful and wrap the fork action & put pid into cgroup.procs, > is there any LTP API can replace this function? Could you help give > example. IMO you don't need to wrap fork or SAFE_CG_PRINTF, just write it inline. >> > +{ >> > + int pid; >> > + >> > + pid = SAFE_FORK(); >> > + if (pid == 0) { >> > + SAFE_CG_PRINTF(cg, "cgroup.procs", "%d", getpid()); >> > + fn(); >> > + } >> > + >> > + return pid; >> > +} >> > + >> > +static int cg_wait_for_proc_count(const struct tst_cg_group *cg, int count) >> > +{ >> > + int attempts; >> > + char *ptr; >> > + >> > + for (attempts = 100; attempts >= 0; attempts--) { >> > + int nr = 0; >> > + >> > + SAFE_CG_READ(cg, "cgroup.procs", buf, buf_len); >> > + >> > + for (ptr = buf; *ptr; ptr++) >> > + if (*ptr == '\n') >> > + nr++; >> > + >> > + if (nr >= count) >> > + return 0; >> > + >> > + usleep(100000); >> >> It's best to avoid arbitrary sleep values and attempts. You could use >> TST_CHECKPOINT* or increment a counter in some shared memory with >> SAFE_MMAP and tst_atomic_inc. >> > I will try to use TST_CHECKPOINT* to sync before call this function >> > + } >> > + >> > + return -1; >> > +} >> > + >> > +static void run(void) >> > +{ >> > + pid_t pids[MAX_PID_NUM]; >> > + int i; >> > + >> > + cg_child_test_simple = tst_cg_group_mk(tst_cg, >> > "cg_test_simple"); >> > + >> > + memset(buf, 0, buf_len); >> >> IIRC guarded buffers are zeroed already. > Already explained by Li Wang in other email. >> >> > + >> > + for (i = 0; i < pid_num; i++) >> > + pids[i] = cg_run_nowait(cg_child_test_simple, child_fn); >> >> If the parent is killed and the children are moved then they will return >> and cause a fork bomb. > There is no extra fork action in child_fn so all child_fn will > reparent and exit. I don't see how it will exit? It seems like it will just return. Possibly I just missed it, but that's why I have an issue with the function pointer as well. > So i do not think fork bomb will happen. >> >> This is not obvious because of the unecessary indirection (function >> pointer and functions). >> >> > + >> > + TST_EXP_PASS(cg_wait_for_proc_count(cg_child_test_simple, >> > pid_num)); >> >> If this fails then there will be little information to debug it. This is >> a common issue with the self tests which we will be importing into the LTP. >> > Add extra log info into this function maybe help, what's your > suggestion? Yes, something like that. >> > + SAFE_CG_PRINTF(cg_child_test_simple, "cgroup.kill", "%d", 1); >> > + >> > + for (i = 0; i < pid_num; i++) { >> > + /* wait_for_pid(pids[i]); */ >> > + TST_EXP_PASS_SILENT(wait_for_pid(pids[i]) == SIGKILL); >> >> It seems wait_for_pid will never == SIGKILL. The function does not >> inspect the signal a process was killed with at all. >> >> The test passes becaues this is not the correct use of TST_EXP_PASS*. > Good catch! Thanks a lot for finding this, i should use WIFSIGNALED > to translate status and check children killed by SIGKILL, will fix this > in next patch. >> >> > + } >> > + >> > + cg_child_test_simple = tst_cg_group_rm(cg_child_test_simple); >> > +} >> > + >> > +static void setup(void) >> > +{ >> > + buf = tst_alloc(buf_len); >> >> Simple allocations like this can be done in the test struct. > This already discussed with Wang Li, compile error will happen since buf_len > not fixed in my case. >> >> > +} >> > + >> > +static struct tst_test test = { >> > + .test_all = run, >> > + .setup = setup, >> > + .forks_child = 1, >> > + .max_runtime = 15, >> > + .needs_cgroup_ctrls = (const char *const []){ "memory", NULL }, >> >> Why do we need the memory controller? >> >> If it is just to make the LTP library happy, then you can change the >> library instead (e.g. add a "cgroup" pseudo controller if we didn't do >> that already). > You guess right, i just go quick way to let LTP happy xD > I will check library and try to implement this. > > Thanks again for your valuable feedback! Thanks! >> >> > + .needs_cgroup_ver = TST_CG_V2, >> > +}; >> > -- >> > 2.35.3 >> >> -- >> Thank you, >> Richard. -- Thank you, Richard. -- Mailing list info: https://lists.linux.it/listinfo/ltp