From: Daniel Bristot de Oliveira bristot@kernel.org
[ Upstream commit dada03db9bb1984826e61cfcf1418ac73848324d ]
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.
Link: https://lkml.kernel.org/r/e8276e122ee9eb2c5a0ba8e673fb6488b924b825.165242357...
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 Reviewed-by: Daniel Wagner dwagner@suse.de Signed-off-by: Daniel Bristot de Oliveira bristot@kernel.org Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org Signed-off-by: Sasha Levin sashal@kernel.org --- tools/tracing/rtla/Makefile | 2 +- tools/tracing/rtla/README.txt | 1 - tools/tracing/rtla/src/utils.c | 106 ++++++++++++++++++++++++++------- tools/tracing/rtla/src/utils.h | 3 +- 4 files changed, 88 insertions(+), 24 deletions(-)
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..5352167a1e75 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 +262,107 @@ int __set_sched_attr(int pid, struct sched_attr *attr)
return 0; } + +/* + * 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. + * + * 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 + * set_comm_sched_attr - set sched params to threads starting with char *comm_prefix * - * 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 + * 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); + return 1; }
- memset(&task, 0, sizeof(task)); + procfs = opendir("/proc"); + if (!procfs) { + err_msg("Could not open procfs\n"); + return 1; + }
- while (readproc(ptp, &task)) { - retval = strncmp(comm, task.cmd, strlen(comm)); - if (retval) + while ((proc_entry = readdir(procfs))) { + + 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);