* [PATCH v2] perf ftrace: Fix the buffer size in __write_tracing_file @ 2018-02-08 8:13 changbin.du 2018-02-12 1:55 ` Namhyung Kim 0 siblings, 1 reply; 5+ messages in thread From: changbin.du @ 2018-02-08 8:13 UTC (permalink / raw) To: jolsa Cc: peterz, mingo, acme, namhyung, linux-kernel, linux-perf-users, Changbin Du From: Changbin Du <changbin.du@intel.com> The terminal character '\0' should take into account into size of the string buffer. Without this fix, the '--graph-funcs', '--nograph-funcs' and '--trace-funcs' options didn't work as expected when the <func> doesn't exist. If usersapce writes a non-terminated string, the kernel side will always return success but actually no filter applied. As discussed before, the kernel now support '\0' to mark the end of string: https://lkml.org/lkml/2018/1/16/116 After this fix in userspace, the perf will report correct error state. Also let it print an error if reset_tracing_files() fails. The problem: $ sudo ./perf ftrace -a --graph-depth 1 --graph-funcs abcdefg 0) 0.140 us | rcu_all_qs(); 3) 0.304 us | mutex_unlock(); 0) 0.153 us | find_vma(); 3) 0.088 us | __fsnotify_parent(); 0) 6.145 us | handle_mm_fault(); 3) 0.089 us | fsnotify(); 3) 0.161 us | __sb_end_write(); 3) 0.710 us | SyS_close(); 3) 7.848 us | exit_to_usermode_loop(); On above example, I specified function filter 'abcdefg' but all functions are enabled. The expected error is hidden. Signed-off-by: Changbin Du <changbin.du@intel.com> --- tools/perf/builtin-ftrace.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c index 25a42ac..a87e9b3 100644 --- a/tools/perf/builtin-ftrace.c +++ b/tools/perf/builtin-ftrace.c @@ -69,7 +69,7 @@ static int __write_tracing_file(const char *name, const char *val, bool append) { char *file; int fd, ret = -1; - ssize_t size = strlen(val); + ssize_t size = strlen(val) + 1; int flags = O_WRONLY; char errbuf[512]; @@ -280,8 +280,10 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv) signal(SIGCHLD, sig_handler); signal(SIGPIPE, sig_handler); - if (reset_tracing_files(ftrace) < 0) + if (reset_tracing_files(ftrace) < 0) { + pr_err("failed to reset ftrace\n"); goto out; + } /* reset ftrace buffer */ if (write_tracing_file("trace", "0") < 0) -- 2.7.4 ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH v2] perf ftrace: Fix the buffer size in __write_tracing_file 2018-02-08 8:13 [PATCH v2] perf ftrace: Fix the buffer size in __write_tracing_file changbin.du @ 2018-02-12 1:55 ` Namhyung Kim 2018-02-12 4:48 ` Du, Changbin 0 siblings, 1 reply; 5+ messages in thread From: Namhyung Kim @ 2018-02-12 1:55 UTC (permalink / raw) To: changbin.du Cc: jolsa, peterz, mingo, acme, linux-kernel, linux-perf-users, kernel-team Hello, On Thu, Feb 08, 2018 at 04:13:20PM +0800, changbin.du@intel.com wrote: > From: Changbin Du <changbin.du@intel.com> > > The terminal character '\0' should take into account into size of the > string buffer. Without this fix, the '--graph-funcs', '--nograph-funcs' > and '--trace-funcs' options didn't work as expected when the <func> > doesn't exist. If usersapce writes a non-terminated string, the kernel > side will always return success but actually no filter applied. > > As discussed before, the kernel now support '\0' to mark the end of string: > https://lkml.org/lkml/2018/1/16/116 > > After this fix in userspace, the perf will report correct error state. Also > let it print an error if reset_tracing_files() fails. But what about old kernels? IIRC there was an error with this change. Thanks, Namhyung > > The problem: > $ sudo ./perf ftrace -a --graph-depth 1 --graph-funcs abcdefg > 0) 0.140 us | rcu_all_qs(); > 3) 0.304 us | mutex_unlock(); > 0) 0.153 us | find_vma(); > 3) 0.088 us | __fsnotify_parent(); > 0) 6.145 us | handle_mm_fault(); > 3) 0.089 us | fsnotify(); > 3) 0.161 us | __sb_end_write(); > 3) 0.710 us | SyS_close(); > 3) 7.848 us | exit_to_usermode_loop(); > > On above example, I specified function filter 'abcdefg' but all functions > are enabled. The expected error is hidden. > > Signed-off-by: Changbin Du <changbin.du@intel.com> > --- > tools/perf/builtin-ftrace.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c > index 25a42ac..a87e9b3 100644 > --- a/tools/perf/builtin-ftrace.c > +++ b/tools/perf/builtin-ftrace.c > @@ -69,7 +69,7 @@ static int __write_tracing_file(const char *name, const char *val, bool append) > { > char *file; > int fd, ret = -1; > - ssize_t size = strlen(val); > + ssize_t size = strlen(val) + 1; > int flags = O_WRONLY; > char errbuf[512]; > > @@ -280,8 +280,10 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv) > signal(SIGCHLD, sig_handler); > signal(SIGPIPE, sig_handler); > > - if (reset_tracing_files(ftrace) < 0) > + if (reset_tracing_files(ftrace) < 0) { > + pr_err("failed to reset ftrace\n"); > goto out; > + } > > /* reset ftrace buffer */ > if (write_tracing_file("trace", "0") < 0) > -- > 2.7.4 > ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] perf ftrace: Fix the buffer size in __write_tracing_file 2018-02-12 1:55 ` Namhyung Kim @ 2018-02-12 4:48 ` Du, Changbin 2018-02-12 6:15 ` Namhyung Kim 0 siblings, 1 reply; 5+ messages in thread From: Du, Changbin @ 2018-02-12 4:48 UTC (permalink / raw) To: Namhyung Kim Cc: changbin.du, jolsa, peterz, mingo, acme, linux-kernel, linux-perf-users, kernel-team Hi, On Mon, Feb 12, 2018 at 10:55:27AM +0900, Namhyung Kim wrote: > Hello, > > On Thu, Feb 08, 2018 at 04:13:20PM +0800, changbin.du@intel.com wrote: > > From: Changbin Du <changbin.du@intel.com> > > > > The terminal character '\0' should take into account into size of the > > string buffer. Without this fix, the '--graph-funcs', '--nograph-funcs' > > and '--trace-funcs' options didn't work as expected when the <func> > > doesn't exist. If usersapce writes a non-terminated string, the kernel > > side will always return success but actually no filter applied. > > > > As discussed before, the kernel now support '\0' to mark the end of string: > > https://lkml.org/lkml/2018/1/16/116 > > > > After this fix in userspace, the perf will report correct error state. Also > > let it print an error if reset_tracing_files() fails. > > But what about old kernels? IIRC there was an error with this change. > Yes, you're right. I can't find a good compitable change. So what is the compatibilty policy for perf? If it must work with recent kernel, I think the only idea is leave as it was. > Thanks, > Namhyung > > > > > > The problem: > > $ sudo ./perf ftrace -a --graph-depth 1 --graph-funcs abcdefg > > 0) 0.140 us | rcu_all_qs(); > > 3) 0.304 us | mutex_unlock(); > > 0) 0.153 us | find_vma(); > > 3) 0.088 us | __fsnotify_parent(); > > 0) 6.145 us | handle_mm_fault(); > > 3) 0.089 us | fsnotify(); > > 3) 0.161 us | __sb_end_write(); > > 3) 0.710 us | SyS_close(); > > 3) 7.848 us | exit_to_usermode_loop(); > > > > On above example, I specified function filter 'abcdefg' but all functions > > are enabled. The expected error is hidden. > > > > Signed-off-by: Changbin Du <changbin.du@intel.com> > > --- > > tools/perf/builtin-ftrace.c | 6 ++++-- > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c > > index 25a42ac..a87e9b3 100644 > > --- a/tools/perf/builtin-ftrace.c > > +++ b/tools/perf/builtin-ftrace.c > > @@ -69,7 +69,7 @@ static int __write_tracing_file(const char *name, const char *val, bool append) > > { > > char *file; > > int fd, ret = -1; > > - ssize_t size = strlen(val); > > + ssize_t size = strlen(val) + 1; > > int flags = O_WRONLY; > > char errbuf[512]; > > > > @@ -280,8 +280,10 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv) > > signal(SIGCHLD, sig_handler); > > signal(SIGPIPE, sig_handler); > > > > - if (reset_tracing_files(ftrace) < 0) > > + if (reset_tracing_files(ftrace) < 0) { > > + pr_err("failed to reset ftrace\n"); > > goto out; > > + } > > > > /* reset ftrace buffer */ > > if (write_tracing_file("trace", "0") < 0) > > -- > > 2.7.4 > > -- Thanks, Changbin Du ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] perf ftrace: Fix the buffer size in __write_tracing_file 2018-02-12 4:48 ` Du, Changbin @ 2018-02-12 6:15 ` Namhyung Kim 2018-02-13 0:18 ` Du, Changbin 0 siblings, 1 reply; 5+ messages in thread From: Namhyung Kim @ 2018-02-12 6:15 UTC (permalink / raw) To: Du, Changbin Cc: jolsa, peterz, mingo, acme, linux-kernel, linux-perf-users, kernel-team, rostedt On Mon, Feb 12, 2018 at 12:48:15PM +0800, Du, Changbin wrote: > Hi, > > On Mon, Feb 12, 2018 at 10:55:27AM +0900, Namhyung Kim wrote: > > Hello, > > > > On Thu, Feb 08, 2018 at 04:13:20PM +0800, changbin.du@intel.com wrote: > > > From: Changbin Du <changbin.du@intel.com> > > > > > > The terminal character '\0' should take into account into size of the > > > string buffer. Without this fix, the '--graph-funcs', '--nograph-funcs' > > > and '--trace-funcs' options didn't work as expected when the <func> > > > doesn't exist. If usersapce writes a non-terminated string, the kernel > > > side will always return success but actually no filter applied. > > > > > > As discussed before, the kernel now support '\0' to mark the end of string: > > > https://lkml.org/lkml/2018/1/16/116 > > > > > > After this fix in userspace, the perf will report correct error state. Also > > > let it print an error if reset_tracing_files() fails. > > > > But what about old kernels? IIRC there was an error with this change. > > > Yes, you're right. I can't find a good compitable change. So what is the compatibilty policy for perf? > If it must work with recent kernel, I think the only idea is leave as it was. It should support *both* of kernels. I suggest adding a space after function name. You can simply call write(fd, " ", 1) IMHO. Thanks, Namhyung > > > > > > > > > > The problem: > > > $ sudo ./perf ftrace -a --graph-depth 1 --graph-funcs abcdefg > > > 0) 0.140 us | rcu_all_qs(); > > > 3) 0.304 us | mutex_unlock(); > > > 0) 0.153 us | find_vma(); > > > 3) 0.088 us | __fsnotify_parent(); > > > 0) 6.145 us | handle_mm_fault(); > > > 3) 0.089 us | fsnotify(); > > > 3) 0.161 us | __sb_end_write(); > > > 3) 0.710 us | SyS_close(); > > > 3) 7.848 us | exit_to_usermode_loop(); > > > > > > On above example, I specified function filter 'abcdefg' but all functions > > > are enabled. The expected error is hidden. > > > > > > Signed-off-by: Changbin Du <changbin.du@intel.com> > > > --- > > > tools/perf/builtin-ftrace.c | 6 ++++-- > > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > > > diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c > > > index 25a42ac..a87e9b3 100644 > > > --- a/tools/perf/builtin-ftrace.c > > > +++ b/tools/perf/builtin-ftrace.c > > > @@ -69,7 +69,7 @@ static int __write_tracing_file(const char *name, const char *val, bool append) > > > { > > > char *file; > > > int fd, ret = -1; > > > - ssize_t size = strlen(val); > > > + ssize_t size = strlen(val) + 1; > > > int flags = O_WRONLY; > > > char errbuf[512]; > > > > > > @@ -280,8 +280,10 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv) > > > signal(SIGCHLD, sig_handler); > > > signal(SIGPIPE, sig_handler); > > > > > > - if (reset_tracing_files(ftrace) < 0) > > > + if (reset_tracing_files(ftrace) < 0) { > > > + pr_err("failed to reset ftrace\n"); > > > goto out; > > > + } > > > > > > /* reset ftrace buffer */ > > > if (write_tracing_file("trace", "0") < 0) > > > -- > > > 2.7.4 > > > > > -- > Thanks, > Changbin Du ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] perf ftrace: Fix the buffer size in __write_tracing_file 2018-02-12 6:15 ` Namhyung Kim @ 2018-02-13 0:18 ` Du, Changbin 0 siblings, 0 replies; 5+ messages in thread From: Du, Changbin @ 2018-02-13 0:18 UTC (permalink / raw) To: Namhyung Kim Cc: Du, Changbin, jolsa@redhat.com, peterz@infradead.org, mingo@redhat.com, acme@kernel.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, kernel-team@lge.com, rostedt@goodmis.org On Sun, Feb 11, 2018 at 10:15:10PM -0800, Namhyung Kim wrote: > On Mon, Feb 12, 2018 at 12:48:15PM +0800, Du, Changbin wrote: > > Hi, > > > > On Mon, Feb 12, 2018 at 10:55:27AM +0900, Namhyung Kim wrote: > > > Hello, > > > > > > On Thu, Feb 08, 2018 at 04:13:20PM +0800, changbin.du@intel.com wrote: > > > > From: Changbin Du <changbin.du@intel.com> > > > > > > > > The terminal character '\0' should take into account into size of the > > > > string buffer. Without this fix, the '--graph-funcs', '--nograph-funcs' > > > > and '--trace-funcs' options didn't work as expected when the <func> > > > > doesn't exist. If usersapce writes a non-terminated string, the kernel > > > > side will always return success but actually no filter applied. > > > > > > > > As discussed before, the kernel now support '\0' to mark the end of string: > > > > https://lkml.org/lkml/2018/1/16/116 > > > > > > > > After this fix in userspace, the perf will report correct error state. Also > > > > let it print an error if reset_tracing_files() fails. > > > > > > But what about old kernels? IIRC there was an error with this change. > > > > > Yes, you're right. I can't find a good compitable change. So what is the compatibilty policy for perf? > > If it must work with recent kernel, I think the only idea is leave as it was. > > It should support *both* of kernels. I suggest adding a space after > function name. You can simply call write(fd, " ", 1) IMHO. > hmm, I see. I will try it later mabye tommorow. Thanks! > Thanks, > Namhyung > > > > > > > > > > > > > > > > The problem: > > > > $ sudo ./perf ftrace -a --graph-depth 1 --graph-funcs abcdefg > > > > 0) 0.140 us | rcu_all_qs(); > > > > 3) 0.304 us | mutex_unlock(); > > > > 0) 0.153 us | find_vma(); > > > > 3) 0.088 us | __fsnotify_parent(); > > > > 0) 6.145 us | handle_mm_fault(); > > > > 3) 0.089 us | fsnotify(); > > > > 3) 0.161 us | __sb_end_write(); > > > > 3) 0.710 us | SyS_close(); > > > > 3) 7.848 us | exit_to_usermode_loop(); > > > > > > > > On above example, I specified function filter 'abcdefg' but all functions > > > > are enabled. The expected error is hidden. > > > > > > > > Signed-off-by: Changbin Du <changbin.du@intel.com> > > > > --- > > > > tools/perf/builtin-ftrace.c | 6 ++++-- > > > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > > > > > diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c > > > > index 25a42ac..a87e9b3 100644 > > > > --- a/tools/perf/builtin-ftrace.c > > > > +++ b/tools/perf/builtin-ftrace.c > > > > @@ -69,7 +69,7 @@ static int __write_tracing_file(const char *name, const char *val, bool append) > > > > { > > > > char *file; > > > > int fd, ret = -1; > > > > - ssize_t size = strlen(val); > > > > + ssize_t size = strlen(val) + 1; > > > > int flags = O_WRONLY; > > > > char errbuf[512]; > > > > > > > > @@ -280,8 +280,10 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv) > > > > signal(SIGCHLD, sig_handler); > > > > signal(SIGPIPE, sig_handler); > > > > > > > > - if (reset_tracing_files(ftrace) < 0) > > > > + if (reset_tracing_files(ftrace) < 0) { > > > > + pr_err("failed to reset ftrace\n"); > > > > goto out; > > > > + } > > > > > > > > /* reset ftrace buffer */ > > > > if (write_tracing_file("trace", "0") < 0) > > > > -- > > > > 2.7.4 > > > > > > > > -- > > Thanks, > > Changbin Du -- Thanks, Changbin Du ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2018-02-13 0:18 UTC | newest] Thread overview: 5+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2018-02-08 8:13 [PATCH v2] perf ftrace: Fix the buffer size in __write_tracing_file changbin.du 2018-02-12 1:55 ` Namhyung Kim 2018-02-12 4:48 ` Du, Changbin 2018-02-12 6:15 ` Namhyung Kim 2018-02-13 0:18 ` Du, Changbin
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