| Message ID | 1683026600-13485-9-git-send-email-akaher@vmware.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | tracing: introducing eventfs | expand |
> On 02/05/23, 11:42 PM, "kernel test robot" <lkp@intel.com> wrote: > >> kernel/trace/trace_events.c:2424:17: warning: variable 'd_events' set but not used [-Wunused-but-set-variable] > struct dentry *d_events; > ^ > 1 warning generated. > Steve, with-in event_create_dir(), do we have any scenario when file->event_call->class->system doesn't have TRACE_SYSTEM? And need to execute following: ae63b31e4d0e2e Steven Rostedt 2012-05-03 2437 d_events = parent; looking for your input if we could remove d_events from event_create_dir(). - Ajay > vim +/d_events +2424 kernel/trace/trace_events.c > > ac343da7bc9048 Masami Hiramatsu 2020-09-10 2417 > 1473e4417c79f1 Steven Rostedt 2009-02-24 2418 static int > 7f1d2f8210195c Steven Rostedt (Red Hat 2015-05-05 2419) event_create_dir(struct dentry *parent, struct trace_event_file *file) > 1473e4417c79f1 Steven Rostedt 2009-02-24 2420 { > 2425bcb9240f8c Steven Rostedt (Red Hat 2015-05-05 2421) struct trace_event_call *call = file->event_call; > ae63b31e4d0e2e Steven Rostedt 2012-05-03 2422 struct trace_array *tr = file->tr; > 2fe2002efb23a7 Ajay Kaher 2023-05-02 2423 struct eventfs_file *ef_subsystem = NULL; > ae63b31e4d0e2e Steven Rostedt 2012-05-03 @2424 struct dentry *d_events; > de7b2973903c6c Mathieu Desnoyers 2014-04-08 2425 const char *name; > fd99498989f3b3 Steven Rostedt 2009-02-28 2426 int ret; > 1473e4417c79f1 Steven Rostedt 2009-02-24 2427 > 6ecc2d1ca39177 Steven Rostedt 2009-02-27 2428 /* > 6ecc2d1ca39177 Steven Rostedt 2009-02-27 2429 * If the trace point header did not define TRACE_SYSTEM > 6ecc2d1ca39177 Steven Rostedt 2009-02-27 2430 * then the system would be called "TRACE_SYSTEM". > 6ecc2d1ca39177 Steven Rostedt 2009-02-27 2431 */ > ae63b31e4d0e2e Steven Rostedt 2012-05-03 2432 if (strcmp(call->class->system, TRACE_SYSTEM) != 0) { > 2fe2002efb23a7 Ajay Kaher 2023-05-02 2433 ef_subsystem = event_subsystem_dir(tr, call->class->system, file, parent); > 2fe2002efb23a7 Ajay Kaher 2023-05-02 2434 if (!ef_subsystem) > ae63b31e4d0e2e Steven Rostedt 2012-05-03 2435 return -ENOMEM; > ae63b31e4d0e2e Steven Rostedt 2012-05-03 2436 } else > ae63b31e4d0e2e Steven Rostedt 2012-05-03 2437 d_events = parent; > 6ecc2d1ca39177 Steven Rostedt 2009-02-27 2438 > 687fcc4aee4567 Steven Rostedt (Red Hat 2015-05-13 2439) name = trace_event_name(call); > 2fe2002efb23a7 Ajay Kaher 2023-05-02 2440 file->ef = eventfs_add_dir(name, ef_subsystem, &tr->eventfs_rwsem); > 2fe2002efb23a7 Ajay Kaher 2023-05-02 2441 if (IS_ERR(file->ef)) { > 8434dc9340cd2e Steven Rostedt (Red Hat 2015-01-20 2442) pr_warn("Could not create tracefs '%s' directory\n", name); > 1473e4417c79f1 Steven Rostedt 2009-02-24 2443 return -1; > 1473e4417c79f1 Steven Rostedt 2009-02-24 2444 } > 1473e4417c79f1 Steven Rostedt 2009-02-24 2445 > 9b63776fa3ca96 Steven Rostedt 2012-05-10 2446 if (call->class->reg && !(call->flags & TRACE_EVENT_FL_IGNORE_ENABLE)) > 2fe2002efb23a7 Ajay Kaher 2023-05-02 2447 eventfs_add_file("enable", TRACE_MODE_WRITE, file->ef, file, > 620a30e97febc8 Oleg Nesterov 2013-07-31 2448 &ftrace_enable_fops); > 1473e4417c79f1 Steven Rostedt 2009-02-24 2449
On Tue, 9 May 2023 12:29:23 +0000 Ajay Kaher <akaher@vmware.com> wrote: > > On 02/05/23, 11:42 PM, "kernel test robot" <lkp@intel.com> wrote: > > >> kernel/trace/trace_events.c:2424:17: warning: variable 'd_events' set but not used [-Wunused-but-set-variable] > > struct dentry *d_events; > > ^ > > 1 warning generated. > > > > Steve, with-in event_create_dir(), do we have any scenario when file->event_call->class->system > doesn't have TRACE_SYSTEM? And need to execute following: > > ae63b31e4d0e2e Steven Rostedt 2012-05-03 2437 d_events = parent; > > looking for your input if we could remove d_events from event_create_dir(). > I have hit this in the beginning, but I don't think it's an issue anymore. Perhaps just have it be: if (WARN_ON_ONCE(strcmp(call->class->system, TRACE_SYSTEM) == 0)) return -ENODEV; ef_subsystem = event_subsystem_dir(tr, call->class->system, file, parent); Hmm, how about just add this patch before your patch set: -- Steve From: "Steven Rostedt (Google)" <rostedt@goodmis.org> Subject: [PATCH] tracing: Require all trace events to have a TRACE_SYSTEM The creation of the trace event directory requires that a TRACE_SYSTEM is defined that the trace event directory is added within the system it was defined in. The code handled the case where a TRACE_SYSTEM was not added, and would then add the event at the events directory. But nothing should be doing this. This code also prevents the implementation of creating dynamic dentrys for the eventfs system. As this path has never been hit on correct code, remove it. If it does get hit, issues a WARN_ON_ONCE() and return ENODEV. Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> --- (lightly tested) kernel/trace/trace_events.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 654ffa40457a..16bc5ba45507 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -2424,14 +2424,15 @@ event_create_dir(struct dentry *parent, struct trace_event_file *file) /* * If the trace point header did not define TRACE_SYSTEM - * then the system would be called "TRACE_SYSTEM". + * then the system would be called "TRACE_SYSTEM". This should + * never happen. */ - if (strcmp(call->class->system, TRACE_SYSTEM) != 0) { - d_events = event_subsystem_dir(tr, call->class->system, file, parent); - if (!d_events) - return -ENOMEM; - } else - d_events = parent; + if (WARN_ON_ONCE(strcmp(call->class->system, TRACE_SYSTEM) == 0)) + return -ENODEV; + + d_events = event_subsystem_dir(tr, call->class->system, file, parent); + if (!d_events) + return -ENOMEM; name = trace_event_name(call); file->dir = tracefs_create_dir(name, d_events);
> On 09-May-2023, at 10:15 PM, Steven Rostedt <rostedt@goodmis.org> wrote: > > !! External Email > > On Tue, 9 May 2023 12:29:23 +0000 > Ajay Kaher <akaher@vmware.com> wrote: > >> > On 02/05/23, 11:42 PM, "kernel test robot" <lkp@intel.com> wrote: >>>>> kernel/trace/trace_events.c:2424:17: warning: variable 'd_events' set but not used [-Wunused-but-set-variable] >>> struct dentry *d_events; >>> ^ >>> 1 warning generated. >>> >> >> Steve, with-in event_create_dir(), do we have any scenario when file->event_call->class->system >> doesn't have TRACE_SYSTEM? And need to execute following: >> >> ae63b31e4d0e2e Steven Rostedt 2012-05-03 2437 d_events = parent; >> >> looking for your input if we could remove d_events from event_create_dir(). >> > > I have hit this in the beginning, but I don't think it's an issue > anymore. Perhaps just have it be: > > if (WARN_ON_ONCE(strcmp(call->class->system, TRACE_SYSTEM) == 0)) > return -ENODEV; > > ef_subsystem = event_subsystem_dir(tr, call->class->system, file, parent); > > Hmm, how about just add this patch before your patch set: > Sounds good. Thanks Steve :) Once you will merge below patch, I will rebase this patch in v3. - Ajay > > From: "Steven Rostedt (Google)" <rostedt@goodmis.org> > Subject: [PATCH] tracing: Require all trace events to have a TRACE_SYSTEM > > The creation of the trace event directory requires that a TRACE_SYSTEM is > defined that the trace event directory is added within the system it was > defined in. > > The code handled the case where a TRACE_SYSTEM was not added, and would > then add the event at the events directory. But nothing should be doing > this. This code also prevents the implementation of creating dynamic > dentrys for the eventfs system. > > As this path has never been hit on correct code, remove it. If it does get > hit, issues a WARN_ON_ONCE() and return ENODEV. > > Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> > --- > > (lightly tested) > > kernel/trace/trace_events.c | 15 ++++++++------- > 1 file changed, 8 insertions(+), 7 deletions(-) > > diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c > index 654ffa40457a..16bc5ba45507 100644 > --- a/kernel/trace/trace_events.c > +++ b/kernel/trace/trace_events.c > @@ -2424,14 +2424,15 @@ event_create_dir(struct dentry *parent, struct trace_event_file *file) > > /* > * If the trace point header did not define TRACE_SYSTEM > - * then the system would be called "TRACE_SYSTEM". > + * then the system would be called "TRACE_SYSTEM". This should > + * never happen. > */ > - if (strcmp(call->class->system, TRACE_SYSTEM) != 0) { > - d_events = event_subsystem_dir(tr, call->class->system, file, parent); > - if (!d_events) > - return -ENOMEM; > - } else > - d_events = parent; > + if (WARN_ON_ONCE(strcmp(call->class->system, TRACE_SYSTEM) == 0)) > + return -ENODEV; > + > + d_events = event_subsystem_dir(tr, call->class->system, file, parent); > + if (!d_events) > + return -ENOMEM; > > name = trace_event_name(call); > file->dir = tracefs_create_dir(name, d_events); > -- > 2.39.2 > > > !! External Email: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender.
On Wed, 10 May 2023 11:11:15 +0000 Ajay Kaher <akaher@vmware.com> wrote: > Sounds good. Thanks Steve :) > Once you will merge below patch, I will rebase this patch in v3. Feel free to just add it at the start of your queue. You just need to keep the "From" line and it will be added as my patch. -- Steve
> On 13-May-2023, at 4:29 AM, Steven Rostedt <rostedt@goodmis.org> wrote: > > !! External Email > > On Wed, 10 May 2023 11:11:15 +0000 > Ajay Kaher <akaher@vmware.com> wrote: > >> Sounds good. Thanks Steve :) >> Once you will merge below patch, I will rebase this patch in v3. > > Feel free to just add it at the start of your queue. You just need to > keep the "From" line and it will be added as my patch. Ok, I will include in v3. -Ajay
diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c index 76820d3e9..a098d7153 100644 --- a/fs/tracefs/inode.c +++ b/fs/tracefs/inode.c @@ -374,6 +374,23 @@ static const struct super_operations tracefs_super_operations = { .show_options = tracefs_show_options, }; +static void tracefs_dentry_iput(struct dentry *dentry, struct inode *inode) +{ + struct tracefs_inode *ti; + + if (!dentry || !inode) + return; + + ti = get_tracefs(inode); + if (ti && ti->flags & TRACEFS_EVENT_INODE) + eventfs_set_ef_status_free(dentry); + iput(inode); +} + +static const struct dentry_operations tracefs_dentry_operations = { + .d_iput = tracefs_dentry_iput, +}; + static int trace_fill_super(struct super_block *sb, void *data, int silent) { static const struct tree_descr trace_files[] = {{""}}; @@ -396,6 +413,7 @@ static int trace_fill_super(struct super_block *sb, void *data, int silent) goto fail; sb->s_op = &tracefs_super_operations; + sb->s_d_op = &tracefs_dentry_operations; tracefs_apply_options(sb, false); diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h index 0e373222a..696843d46 100644 --- a/include/linux/trace_events.h +++ b/include/linux/trace_events.h @@ -635,6 +635,7 @@ struct trace_event_file { struct list_head list; struct trace_event_call *event_call; struct event_filter __rcu *filter; + struct eventfs_file *ef; struct dentry *dir; struct trace_array *tr; struct trace_subsystem_dir *system; diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 3726725c8..ee9002852 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -1308,7 +1308,7 @@ struct trace_subsystem_dir { struct list_head list; struct event_subsystem *subsystem; struct trace_array *tr; - struct dentry *entry; + struct eventfs_file *ef; int ref_count; int nr_events; }; diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 654ffa404..01bd3dda6 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -988,7 +988,8 @@ static void remove_subsystem(struct trace_subsystem_dir *dir) return; if (!--dir->nr_events) { - tracefs_remove(dir->entry); + if (dir->ef) + eventfs_remove(dir->ef); list_del(&dir->list); __put_system_dir(dir); } @@ -1009,7 +1010,8 @@ static void remove_event_file_dir(struct trace_event_file *file) tracefs_remove(dir); } - + if (file->ef) + eventfs_remove(file->ef); list_del(&file->list); remove_subsystem(file->system); free_event_filter(file->filter); @@ -2295,13 +2297,13 @@ create_new_subsystem(const char *name) return NULL; } -static struct dentry * +static struct eventfs_file * event_subsystem_dir(struct trace_array *tr, const char *name, struct trace_event_file *file, struct dentry *parent) { struct event_subsystem *system, *iter; struct trace_subsystem_dir *dir; - struct dentry *entry; + int res; /* First see if we did not already create this dir */ list_for_each_entry(dir, &tr->systems, list) { @@ -2309,7 +2311,7 @@ event_subsystem_dir(struct trace_array *tr, const char *name, if (strcmp(system->name, name) == 0) { dir->nr_events++; file->system = dir; - return dir->entry; + return dir->ef; } } @@ -2333,8 +2335,8 @@ event_subsystem_dir(struct trace_array *tr, const char *name, } else __get_system(system); - dir->entry = tracefs_create_dir(name, parent); - if (!dir->entry) { + dir->ef = eventfs_add_subsystem_dir(name, parent, &tr->eventfs_rwsem); + if (IS_ERR(dir->ef)) { pr_warn("Failed to create system directory %s\n", name); __put_system(system); goto out_free; @@ -2349,22 +2351,22 @@ event_subsystem_dir(struct trace_array *tr, const char *name, /* the ftrace system is special, do not create enable or filter files */ if (strcmp(name, "ftrace") != 0) { - entry = tracefs_create_file("filter", TRACE_MODE_WRITE, - dir->entry, dir, + res = eventfs_add_file("filter", TRACE_MODE_WRITE, + dir->ef, dir, &ftrace_subsystem_filter_fops); - if (!entry) { + if (res) { kfree(system->filter); system->filter = NULL; pr_warn("Could not create tracefs '%s/filter' entry\n", name); } - trace_create_file("enable", TRACE_MODE_WRITE, dir->entry, dir, + eventfs_add_file("enable", TRACE_MODE_WRITE, dir->ef, dir, &ftrace_system_enable_fops); } list_add(&dir->list, &tr->systems); - return dir->entry; + return dir->ef; out_free: kfree(dir); @@ -2418,6 +2420,7 @@ event_create_dir(struct dentry *parent, struct trace_event_file *file) { struct trace_event_call *call = file->event_call; struct trace_array *tr = file->tr; + struct eventfs_file *ef_subsystem = NULL; struct dentry *d_events; const char *name; int ret; @@ -2427,26 +2430,26 @@ event_create_dir(struct dentry *parent, struct trace_event_file *file) * then the system would be called "TRACE_SYSTEM". */ if (strcmp(call->class->system, TRACE_SYSTEM) != 0) { - d_events = event_subsystem_dir(tr, call->class->system, file, parent); - if (!d_events) + ef_subsystem = event_subsystem_dir(tr, call->class->system, file, parent); + if (!ef_subsystem) return -ENOMEM; } else d_events = parent; name = trace_event_name(call); - file->dir = tracefs_create_dir(name, d_events); - if (!file->dir) { + file->ef = eventfs_add_dir(name, ef_subsystem, &tr->eventfs_rwsem); + if (IS_ERR(file->ef)) { pr_warn("Could not create tracefs '%s' directory\n", name); return -1; } if (call->class->reg && !(call->flags & TRACE_EVENT_FL_IGNORE_ENABLE)) - trace_create_file("enable", TRACE_MODE_WRITE, file->dir, file, + eventfs_add_file("enable", TRACE_MODE_WRITE, file->ef, file, &ftrace_enable_fops); #ifdef CONFIG_PERF_EVENTS if (call->event.type && call->class->reg) - trace_create_file("id", TRACE_MODE_READ, file->dir, + eventfs_add_file("id", TRACE_MODE_READ, file->ef, (void *)(long)call->event.type, &ftrace_event_id_fops); #endif @@ -2462,27 +2465,27 @@ event_create_dir(struct dentry *parent, struct trace_event_file *file) * triggers or filters. */ if (!(call->flags & TRACE_EVENT_FL_IGNORE_ENABLE)) { - trace_create_file("filter", TRACE_MODE_WRITE, file->dir, + eventfs_add_file("filter", TRACE_MODE_WRITE, file->ef, file, &ftrace_event_filter_fops); - trace_create_file("trigger", TRACE_MODE_WRITE, file->dir, + eventfs_add_file("trigger", TRACE_MODE_WRITE, file->ef, file, &event_trigger_fops); } #ifdef CONFIG_HIST_TRIGGERS - trace_create_file("hist", TRACE_MODE_READ, file->dir, file, + eventfs_add_file("hist", TRACE_MODE_READ, file->ef, file, &event_hist_fops); #endif #ifdef CONFIG_HIST_TRIGGERS_DEBUG - trace_create_file("hist_debug", TRACE_MODE_READ, file->dir, file, + eventfs_add_file("hist_debug", TRACE_MODE_READ, file->ef, file, &event_hist_debug_fops); #endif - trace_create_file("format", TRACE_MODE_READ, file->dir, call, + eventfs_add_file("format", TRACE_MODE_READ, file->ef, call, &ftrace_event_format_fops); #ifdef CONFIG_TRACE_EVENT_INJECT if (call->event.type && call->class->reg) - trace_create_file("inject", 0200, file->dir, file, + eventfs_add_file("inject", 0200, file->ef, file, &event_inject_fops); #endif @@ -3635,21 +3638,22 @@ create_event_toplevel_files(struct dentry *parent, struct trace_array *tr) { struct dentry *d_events; struct dentry *entry; + int error = 0; entry = trace_create_file("set_event", TRACE_MODE_WRITE, parent, tr, &ftrace_set_event_fops); if (!entry) return -ENOMEM; - d_events = tracefs_create_dir("events", parent); - if (!d_events) { + d_events = eventfs_create_events_dir("events", parent, &tr->eventfs_rwsem); + if (IS_ERR(d_events)) { pr_warn("Could not create tracefs 'events' directory\n"); return -ENOMEM; } - entry = trace_create_file("enable", TRACE_MODE_WRITE, d_events, + error = eventfs_add_top_file("enable", TRACE_MODE_WRITE, d_events, tr, &ftrace_tr_enable_fops); - if (!entry) + if (error) return -ENOMEM; /* There are not as crucial, just warn if they are not created */ @@ -3662,11 +3666,11 @@ create_event_toplevel_files(struct dentry *parent, struct trace_array *tr) &ftrace_set_event_notrace_pid_fops); /* ring buffer internal formats */ - trace_create_file("header_page", TRACE_MODE_READ, d_events, + eventfs_add_top_file("header_page", TRACE_MODE_READ, d_events, ring_buffer_print_page_header, &ftrace_show_header_fops); - trace_create_file("header_event", TRACE_MODE_READ, d_events, + eventfs_add_top_file("header_event", TRACE_MODE_READ, d_events, ring_buffer_print_entry_header, &ftrace_show_header_fops); @@ -3754,7 +3758,7 @@ int event_trace_del_tracer(struct trace_array *tr) down_write(&trace_event_sem); __trace_remove_event_dirs(tr); - tracefs_remove(tr->event_dir); + eventfs_remove_events_dir(tr->event_dir); up_write(&trace_event_sem); tr->event_dir = NULL;