From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B1F12173 for ; Sat, 15 Jan 2022 20:36:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C48AEC36AE5; Sat, 15 Jan 2022 20:36:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1642278969; bh=j81iu10IGA5MM7vZ+4Xflpm3VzuElFYMdZD244D7f5U=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=LKaqP8ny21GJ1HjC2QlE+3d0zehf1jptH+vE+ls2WL1yuH+ubKPqPnkvgRfUS13zT Da3189wOonGl3l1jcwzRT2HpFZ0nbhterUBop+eiG/IM3Q6tfwmnK3Cn784s/9FBlH 6YY1uiMt8KwkYgpOZ7B3YWKc3Ran2ldQIEokF1wUBEr0WxyUbtZG7e80YDr3kqXkqh Y3ByVd/CyJZENnrMaFfMddBbZ9wZU7s4RyfrU65exjdfmAgHShs0Hvl0Kl+X5rlrjk pBIUf5mUfeLrwimXIFCsUOvgldMGljupoaN5bPB506zOPO7fB6KDrtqq2sYlYBg5KO gjhRphO614Zeg== Date: Sat, 15 Jan 2022 13:36:04 -0700 From: Nathan Chancellor To: Steven Rostedt , Yinan Liu Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton , kernel test robot , kernel test robot , llvm@lists.linux.dev Subject: Re: [for-next][PATCH 10/31] scripts: ftrace - move the sort-processing in ftrace_init Message-ID: References: <20220111173030.999527342@goodmis.org> <20220111173115.079437896@goodmis.org> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220111173115.079437896@goodmis.org> Hi Steven and Yinan, On Tue, Jan 11, 2022 at 12:30:41PM -0500, Steven Rostedt wrote: > From: Yinan Liu > > When the kernel starts, the initialization of ftrace takes > up a portion of the time (approximately 6~8ms) to sort mcount > addresses. We can save this time by moving mcount-sorting to > compile time. > > Link: https://lkml.kernel.org/r/20211212113358.34208-2-yinan@linux.alibaba.com > > Signed-off-by: Yinan Liu > Reported-by: kernel test robot > Reported-by: kernel test robot > Signed-off-by: Steven Rostedt This change as commit 72b3942a173c ("scripts: ftrace - move the sort-processing in ftrace_init") in -next causes a bunch of warnings at the beginning of the build when using clang as the host compiler: $ make -skj"$(nproc)" LLVM=1 distclean allmodconfig init/main.o In file included from scripts/sorttable.c:195: scripts/sorttable.h:380:6: warning: variable 'mcount_sort_thread' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized] if (!mstruct.init_data_sec || !_start_mcount_loc || !_stop_mcount_loc) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ scripts/sorttable.h:479:6: note: uninitialized use occurs here if (mcount_sort_thread) { ^~~~~~~~~~~~~~~~~~ scripts/sorttable.h:380:2: note: remove the 'if' if its condition is always false if (!mstruct.init_data_sec || !_start_mcount_loc || !_stop_mcount_loc) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ scripts/sorttable.h:380:6: warning: variable 'mcount_sort_thread' is used uninitialized whenever '||' condition is true [-Wsometimes-uninitialized] if (!mstruct.init_data_sec || !_start_mcount_loc || !_stop_mcount_loc) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ scripts/sorttable.h:479:6: note: uninitialized use occurs here if (mcount_sort_thread) { ^~~~~~~~~~~~~~~~~~ scripts/sorttable.h:380:6: note: remove the '||' if its condition is always false if (!mstruct.init_data_sec || !_start_mcount_loc || !_stop_mcount_loc) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ scripts/sorttable.h:380:6: warning: variable 'mcount_sort_thread' is used uninitialized whenever '||' condition is true [-Wsometimes-uninitialized] if (!mstruct.init_data_sec || !_start_mcount_loc || !_stop_mcount_loc) { ^~~~~~~~~~~~~~~~~~~~~~ scripts/sorttable.h:479:6: note: uninitialized use occurs here if (mcount_sort_thread) { ^~~~~~~~~~~~~~~~~~ scripts/sorttable.h:380:6: note: remove the '||' if its condition is always false if (!mstruct.init_data_sec || !_start_mcount_loc || !_stop_mcount_loc) { ^~~~~~~~~~~~~~~~~~~~~~~~~ scripts/sorttable.h:288:30: note: initialize the variable 'mcount_sort_thread' to silence this warning pthread_t mcount_sort_thread; ^ = 0 In file included from scripts/sorttable.c:197: scripts/sorttable.h:380:6: warning: variable 'mcount_sort_thread' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized] if (!mstruct.init_data_sec || !_start_mcount_loc || !_stop_mcount_loc) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ scripts/sorttable.h:479:6: note: uninitialized use occurs here if (mcount_sort_thread) { ^~~~~~~~~~~~~~~~~~ scripts/sorttable.h:380:2: note: remove the 'if' if its condition is always false if (!mstruct.init_data_sec || !_start_mcount_loc || !_stop_mcount_loc) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ scripts/sorttable.h:380:6: warning: variable 'mcount_sort_thread' is used uninitialized whenever '||' condition is true [-Wsometimes-uninitialized] if (!mstruct.init_data_sec || !_start_mcount_loc || !_stop_mcount_loc) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ scripts/sorttable.h:479:6: note: uninitialized use occurs here if (mcount_sort_thread) { ^~~~~~~~~~~~~~~~~~ scripts/sorttable.h:380:6: note: remove the '||' if its condition is always false if (!mstruct.init_data_sec || !_start_mcount_loc || !_stop_mcount_loc) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ scripts/sorttable.h:380:6: warning: variable 'mcount_sort_thread' is used uninitialized whenever '||' condition is true [-Wsometimes-uninitialized] if (!mstruct.init_data_sec || !_start_mcount_loc || !_stop_mcount_loc) { ^~~~~~~~~~~~~~~~~~~~~~ scripts/sorttable.h:479:6: note: uninitialized use occurs here if (mcount_sort_thread) { ^~~~~~~~~~~~~~~~~~ scripts/sorttable.h:380:6: note: remove the '||' if its condition is always false if (!mstruct.init_data_sec || !_start_mcount_loc || !_stop_mcount_loc) { ^~~~~~~~~~~~~~~~~~~~~~~~~ scripts/sorttable.h:370:6: warning: variable 'mcount_sort_thread' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized] if (pthread_create(&orc_sort_thread, NULL, ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ scripts/sorttable.h:479:6: note: uninitialized use occurs here if (mcount_sort_thread) { ^~~~~~~~~~~~~~~~~~ scripts/sorttable.h:370:2: note: remove the 'if' if its condition is always false if (pthread_create(&orc_sort_thread, NULL, ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ scripts/sorttable.h:360:6: warning: variable 'mcount_sort_thread' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized] if (orc_ip_size % sizeof(int) != 0 || ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ scripts/sorttable.h:479:6: note: uninitialized use occurs here if (mcount_sort_thread) { ^~~~~~~~~~~~~~~~~~ scripts/sorttable.h:360:2: note: remove the 'if' if its condition is always false if (orc_ip_size % sizeof(int) != 0 || ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ scripts/sorttable.h:360:6: warning: variable 'mcount_sort_thread' is used uninitialized whenever '||' condition is true [-Wsometimes-uninitialized] if (orc_ip_size % sizeof(int) != 0 || ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ scripts/sorttable.h:479:6: note: uninitialized use occurs here if (mcount_sort_thread) { ^~~~~~~~~~~~~~~~~~ scripts/sorttable.h:360:6: note: remove the '||' if its condition is always false if (orc_ip_size % sizeof(int) != 0 || ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ scripts/sorttable.h:360:6: warning: variable 'mcount_sort_thread' is used uninitialized whenever '||' condition is true [-Wsometimes-uninitialized] if (orc_ip_size % sizeof(int) != 0 || ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ scripts/sorttable.h:479:6: note: uninitialized use occurs here if (mcount_sort_thread) { ^~~~~~~~~~~~~~~~~~ scripts/sorttable.h:360:6: note: remove the '||' if its condition is always false if (orc_ip_size % sizeof(int) != 0 || ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ scripts/sorttable.h:353:6: warning: variable 'mcount_sort_thread' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized] if (!g_orc_ip_table || !g_orc_table) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ scripts/sorttable.h:479:6: note: uninitialized use occurs here if (mcount_sort_thread) { ^~~~~~~~~~~~~~~~~~ scripts/sorttable.h:353:2: note: remove the 'if' if its condition is always false if (!g_orc_ip_table || !g_orc_table) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ scripts/sorttable.h:353:6: warning: variable 'mcount_sort_thread' is used uninitialized whenever '||' condition is true [-Wsometimes-uninitialized] if (!g_orc_ip_table || !g_orc_table) { ^~~~~~~~~~~~~~~ scripts/sorttable.h:479:6: note: uninitialized use occurs here if (mcount_sort_thread) { ^~~~~~~~~~~~~~~~~~ scripts/sorttable.h:353:6: note: remove the '||' if its condition is always false if (!g_orc_ip_table || !g_orc_table) { ^~~~~~~~~~~~~~~~~~ scripts/sorttable.h:288:30: note: initialize the variable 'mcount_sort_thread' to silence this warning pthread_t mcount_sort_thread; ^ = 0 12 warnings generated. Should mcount_sort_thread be zero initialized or is there something else going on here? I am currently hunting down a bunch of other regressions so apologies for just the report rather than a patch to fix it. Cheers, Nathan