| Message ID | 553032a74ccdb1e6ae4dda543b7c4430ce8fae1a.1652176288.git.bristot@kernel.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [V3] rtla: Remove procps-ng dependency | expand |
On Tue, May 10, 2022 at 11:57:04AM +0200, Daniel Bristot de Oliveira wrote: > +static int procfs_is_workload_pid(const char *comm_prefix, struct dirent *proc_entry) > +{ > + char buffer[MAX_PATH]; > + int comm_fd, retval; > + char *t_name; > + > + if (proc_entry->d_type != DT_DIR) > + return 0; > + > + if (*proc_entry->d_name == '.') > + return 0; > + > + /* check if the string is a pid */ > + for (t_name = proc_entry->d_name; t_name; t_name++) { > + if (!isdigit(*t_name)) > + break; > + } > + > + if (*t_name != '\0') > + return 0; > + > + snprintf(buffer, MAX_PATH, "/proc/%s/comm", proc_entry->d_name); > + comm_fd = open(buffer, O_RDONLY); > + if (comm_fd < 0) > + return 0; > + > + memset(buffer, 0, MAX_PATH); > + retval = read(comm_fd, buffer, MAX_PATH); > + > + close(comm_fd); > + > + if (retval <= 0) > + return 0; > + > + retval = strncmp(comm_prefix, buffer, strlen(comm_prefix)); > + if (retval) > + return 0; > + > + /* comm already have \n */ > + debug_msg("Found workload pid:%s comm:%s", proc_entry->d_name, buffer); > + > + return 1; > +} > + > +/* > + * set_comm_sched_attr - set sched params to threads starting with char *comm_prefix > + * > + * This function uses /procfs to list the currently running threads and then set the > + * sched_attr *attr to the threads that start with char *comm_prefix. It is > * mainly used to set the priority to the kernel threads created by the > * tracers. > */ > -int set_comm_sched_attr(const char *comm, struct sched_attr *attr) > +int set_comm_sched_attr(const char *comm_prefix, struct sched_attr *attr) > { > - int flags = PROC_FILLCOM | PROC_FILLSTAT; > - PROCTAB *ptp; > - proc_t task; > + struct dirent *proc_entry; > + DIR *procfs; > int retval; > > - ptp = openproc(flags); > - if (!ptp) { > - err_msg("error openproc()\n"); > - return -ENOENT; > + if (strlen(comm_prefix) >= MAX_PATH) { > + err_msg("Command prefix is too long: %d < strlen(%s)\n", > + MAX_PATH, comm_prefix); > + exit(EINVAL); > } > > - memset(&task, 0, sizeof(task)); > + procfs = opendir("/proc"); Maybe you want to check if procfs is a valid handle before using it. > + > + while ((proc_entry = readdir(procfs))) { > > - while (readproc(ptp, &task)) { > - retval = strncmp(comm, task.cmd, strlen(comm)); > - if (retval) > + retval = procfs_is_workload_pid(comm_prefix, proc_entry); > + if (!retval) > continue; > - retval = __set_sched_attr(task.tid, attr); > - if (retval) > + > + /* procfs_is_workload_pid confirmed it is a pid */ > + retval = __set_sched_attr(atoi(proc_entry->d_name), attr); > + if (retval) { > + err_msg("Error setting sched attributes for pid:%s\n", proc_entry->d_name); > goto out_err; > - } > + } > > - closeproc(ptp); > + debug_msg("Set sched attributes for pid:%s\n", proc_entry->d_name); > + } > return 0; > > out_err: > - closeproc(ptp); > + closedir(procfs); > return 1; > } > > diff --git a/tools/tracing/rtla/src/utils.h b/tools/tracing/rtla/src/utils.h > index fa08e374870a..5571afd3b549 100644 > --- a/tools/tracing/rtla/src/utils.h > +++ b/tools/tracing/rtla/src/utils.h > @@ -6,6 +6,7 @@ > * '18446744073709551615\0' > */ > #define BUFF_U64_STR_SIZE 24 > +#define MAX_PATH 1024 linux/limits.h defined MAX_PATH as well, though as 4096. Maybe use that definition? If you want to make it dynamic you could use fpathconf(fd, _PC_PATH_MAX) but one could argue that is over engineering :) Thanks for the fix. Anyway just nitpicking. Reviewed-by: Daniel Wagner <dwagner@suse.de>
On 5/10/22 13:30, Daniel Wagner wrote: > On Tue, May 10, 2022 at 11:57:04AM +0200, Daniel Bristot de Oliveira wrote: >> -int set_comm_sched_attr(const char *comm, struct sched_attr *attr) >> +int set_comm_sched_attr(const char *comm_prefix, struct sched_attr *attr) >> { >> - int flags = PROC_FILLCOM | PROC_FILLSTAT; >> - PROCTAB *ptp; >> - proc_t task; >> + struct dirent *proc_entry; >> + DIR *procfs; >> int retval; >> >> - ptp = openproc(flags); >> - if (!ptp) { >> - err_msg("error openproc()\n"); >> - return -ENOENT; >> + if (strlen(comm_prefix) >= MAX_PATH) { >> + err_msg("Command prefix is too long: %d < strlen(%s)\n", >> + MAX_PATH, comm_prefix); >> + exit(EINVAL); >> } >> >> - memset(&task, 0, sizeof(task)); >> + procfs = opendir("/proc"); > > Maybe you want to check if procfs is a valid handle before using it. Yes I want! >> + >> + while ((proc_entry = readdir(procfs))) { >> >> - while (readproc(ptp, &task)) { >> - retval = strncmp(comm, task.cmd, strlen(comm)); >> - if (retval) >> + retval = procfs_is_workload_pid(comm_prefix, proc_entry); >> + if (!retval) >> continue; >> - retval = __set_sched_attr(task.tid, attr); >> - if (retval) >> + >> + /* procfs_is_workload_pid confirmed it is a pid */ >> + retval = __set_sched_attr(atoi(proc_entry->d_name), attr); >> + if (retval) { >> + err_msg("Error setting sched attributes for pid:%s\n", proc_entry->d_name); >> goto out_err; >> - } >> + } >> >> - closeproc(ptp); >> + debug_msg("Set sched attributes for pid:%s\n", proc_entry->d_name); >> + } >> return 0; >> >> out_err: >> - closeproc(ptp); >> + closedir(procfs); >> return 1; >> } >> >> diff --git a/tools/tracing/rtla/src/utils.h b/tools/tracing/rtla/src/utils.h >> index fa08e374870a..5571afd3b549 100644 >> --- a/tools/tracing/rtla/src/utils.h >> +++ b/tools/tracing/rtla/src/utils.h >> @@ -6,6 +6,7 @@ >> * '18446744073709551615\0' >> */ >> #define BUFF_U64_STR_SIZE 24 >> +#define MAX_PATH 1024 > > linux/limits.h defined MAX_PATH as well, though as 4096. Maybe use that > definition? If you want to make it dynamic you could use fpathconf(fd, > _PC_PATH_MAX) but one could argue that is over engineering :) > > Thanks for the fix. Anyway just nitpicking. Fedora did not find it by default... let's just define our own here. > Reviewed-by: Daniel Wagner <dwagner@suse.de> Thanks! -- Daniel
diff --git a/tools/tracing/rtla/Makefile b/tools/tracing/rtla/Makefile index 5a3226e436ef..523f0a8c38c2 100644 --- a/tools/tracing/rtla/Makefile +++ b/tools/tracing/rtla/Makefile @@ -32,7 +32,7 @@ TRACEFS_HEADERS := $$($(PKG_CONFIG) --cflags libtracefs) CFLAGS := -O -g -DVERSION=\"$(VERSION)\" $(FOPTS) $(MOPTS) $(WOPTS) $(TRACEFS_HEADERS) LDFLAGS := -ggdb -LIBS := $$($(PKG_CONFIG) --libs libtracefs) -lprocps +LIBS := $$($(PKG_CONFIG) --libs libtracefs) SRC := $(wildcard src/*.c) HDR := $(wildcard src/*.h) diff --git a/tools/tracing/rtla/README.txt b/tools/tracing/rtla/README.txt index 0fbad2640b8c..4af3fd40f171 100644 --- a/tools/tracing/rtla/README.txt +++ b/tools/tracing/rtla/README.txt @@ -11,7 +11,6 @@ RTLA depends on the following libraries and tools: - libtracefs - libtraceevent - - procps It also depends on python3-docutils to compile man pages. diff --git a/tools/tracing/rtla/src/utils.c b/tools/tracing/rtla/src/utils.c index 3bd6f64780cf..f2e9fc282da4 100644 --- a/tools/tracing/rtla/src/utils.c +++ b/tools/tracing/rtla/src/utils.c @@ -3,7 +3,7 @@ * Copyright (C) 2021 Red Hat Inc, Daniel Bristot de Oliveira <bristot@kernel.org> */ -#include <proc/readproc.h> +#include <dirent.h> #include <stdarg.h> #include <stdlib.h> #include <string.h> @@ -262,43 +262,103 @@ int __set_sched_attr(int pid, struct sched_attr *attr) return 0; } + /* - * set_comm_sched_attr - set sched params to threads starting with char *comm + * procfs_is_workload_pid - check if a procfs entry contains a comm_prefix* comm + * + * Check if the procfs entry is a directory of a process, and then check if the + * process has a comm with the prefix set in char *comm_prefix. As the + * current users of this function only check for kernel threads, there is no + * need to check for the threads for the process. * - * This function uses procps to list the currently running threads and then - * set the sched_attr *attr to the threads that start with char *comm. It is + * Return: True if the proc_entry contains a comm file with comm_prefix*. + * Otherwise returns false. + */ +static int procfs_is_workload_pid(const char *comm_prefix, struct dirent *proc_entry) +{ + char buffer[MAX_PATH]; + int comm_fd, retval; + char *t_name; + + if (proc_entry->d_type != DT_DIR) + return 0; + + if (*proc_entry->d_name == '.') + return 0; + + /* check if the string is a pid */ + for (t_name = proc_entry->d_name; t_name; t_name++) { + if (!isdigit(*t_name)) + break; + } + + if (*t_name != '\0') + return 0; + + snprintf(buffer, MAX_PATH, "/proc/%s/comm", proc_entry->d_name); + comm_fd = open(buffer, O_RDONLY); + if (comm_fd < 0) + return 0; + + memset(buffer, 0, MAX_PATH); + retval = read(comm_fd, buffer, MAX_PATH); + + close(comm_fd); + + if (retval <= 0) + return 0; + + retval = strncmp(comm_prefix, buffer, strlen(comm_prefix)); + if (retval) + return 0; + + /* comm already have \n */ + debug_msg("Found workload pid:%s comm:%s", proc_entry->d_name, buffer); + + return 1; +} + +/* + * set_comm_sched_attr - set sched params to threads starting with char *comm_prefix + * + * This function uses /procfs to list the currently running threads and then set the + * sched_attr *attr to the threads that start with char *comm_prefix. It is * mainly used to set the priority to the kernel threads created by the * tracers. */ -int set_comm_sched_attr(const char *comm, struct sched_attr *attr) +int set_comm_sched_attr(const char *comm_prefix, struct sched_attr *attr) { - int flags = PROC_FILLCOM | PROC_FILLSTAT; - PROCTAB *ptp; - proc_t task; + struct dirent *proc_entry; + DIR *procfs; int retval; - ptp = openproc(flags); - if (!ptp) { - err_msg("error openproc()\n"); - return -ENOENT; + if (strlen(comm_prefix) >= MAX_PATH) { + err_msg("Command prefix is too long: %d < strlen(%s)\n", + MAX_PATH, comm_prefix); + exit(EINVAL); } - memset(&task, 0, sizeof(task)); + procfs = opendir("/proc"); + + while ((proc_entry = readdir(procfs))) { - while (readproc(ptp, &task)) { - retval = strncmp(comm, task.cmd, strlen(comm)); - if (retval) + retval = procfs_is_workload_pid(comm_prefix, proc_entry); + if (!retval) continue; - retval = __set_sched_attr(task.tid, attr); - if (retval) + + /* procfs_is_workload_pid confirmed it is a pid */ + retval = __set_sched_attr(atoi(proc_entry->d_name), attr); + if (retval) { + err_msg("Error setting sched attributes for pid:%s\n", proc_entry->d_name); goto out_err; - } + } - closeproc(ptp); + debug_msg("Set sched attributes for pid:%s\n", proc_entry->d_name); + } return 0; out_err: - closeproc(ptp); + closedir(procfs); return 1; } diff --git a/tools/tracing/rtla/src/utils.h b/tools/tracing/rtla/src/utils.h index fa08e374870a..5571afd3b549 100644 --- a/tools/tracing/rtla/src/utils.h +++ b/tools/tracing/rtla/src/utils.h @@ -6,6 +6,7 @@ * '18446744073709551615\0' */ #define BUFF_U64_STR_SIZE 24 +#define MAX_PATH 1024 #define container_of(ptr, type, member)({ \ const typeof(((type *)0)->member) *__mptr = (ptr); \ @@ -53,5 +54,5 @@ struct sched_attr { }; int parse_prio(char *arg, struct sched_attr *sched_param); -int set_comm_sched_attr(const char *comm, struct sched_attr *attr); +int set_comm_sched_attr(const char *comm_prefix, struct sched_attr *attr); int set_cpu_dma_latency(int32_t latency);
Daniel Wagner reported to me that readproc.h got deprecated. Also, while the procps-ng library was available on Fedora, it was not available on RHEL, which is a piece of evidence that it was not that used. rtla uses procps-ng only to find the PID of the tracers' workload. I used the procps-ng library to avoid reinventing the wheel. But in this case, reinventing the wheel took me less time than the time we already took trying to work around problems. Implement a function that reads /proc/ entries, checking if: - the entry is a directory - the directory name is composed only of digits (PID) - the directory contains the comm file - the comm file contains a comm that matches the tracers' workload prefix. - then return true; otherwise, return false. And use it instead of procps-ng. Cc: John Kacur <jkacur@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Tao Zhou <tao.zhou@linux.dev> Fixes: b1696371d865 ("rtla: Helper functions for rtla") Reported-by: Daniel Wagner <dwagner@suse.de> Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org> --- Changes from V2: - Add a space in char *t_name; - s/procps/procfs/ in set_comm_sched_attr() comment tools/tracing/rtla/Makefile | 2 +- tools/tracing/rtla/README.txt | 1 - tools/tracing/rtla/src/utils.c | 102 ++++++++++++++++++++++++++------- tools/tracing/rtla/src/utils.h | 3 +- 4 files changed, 84 insertions(+), 24 deletions(-)