Messages in this thread | | | Date | Sat, 15 Jan 2022 13:36:04 -0700 | From | Nathan Chancellor <> | Subject | Re: [for-next][PATCH 10/31] scripts: ftrace - move the sort-processing in ftrace_init |
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Hi Steven and Yinan,
On Tue, Jan 11, 2022 at 12:30:41PM -0500, Steven Rostedt wrote: > From: Yinan Liu <yinan@linux.alibaba.com> > > 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 <yinan@linux.alibaba.com> > Reported-by: kernel test robot <lkp@intel.com> > Reported-by: kernel test robot <oliver.sang@intel.com> > Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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
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