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@xxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Fixes: b1696371d865 ("rtla: Helper functions for rtla")
Reported-by: Daniel Wagner <dwagner@xxxxxxx>
Signed-off-by: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
---
tools/tracing/rtla/Makefile | 2 +-
tools/tracing/rtla/README.txt | 1 -
tools/tracing/rtla/src/utils.c | 83 +++++++++++++++++++++++++++-------
tools/tracing/rtla/src/utils.h | 1 +
4 files changed, 68 insertions(+), 19 deletions(-)
diff --git a/tools/tracing/rtla/Makefile b/tools/tracing/rtla/Makefile
index 11fb417abb42..90b8e20d1118 100644
--- a/tools/tracing/rtla/Makefile
+++ b/tools/tracing/rtla/Makefile
@@ -31,7 +31,7 @@ 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 6c88446f7e74..7bc0b931ddfd 100644
--- a/tools/tracing/rtla/README.txt
+++ b/tools/tracing/rtla/README.txt
@@ -13,7 +13,6 @@ following libraries:
- 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 da2b590edaed..baf9003d5d41 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@xxxxxxxxxx>
*/
-#include <proc/readproc.h>
+#include <dirent.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
@@ -262,6 +262,62 @@ int __set_sched_attr(int pid, struct sched_attr *attr)
return 0;
}
+
+/*
+ * procfs_is_workload_pid - check if a procfs entry contains a workload_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 *workload_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 workload_prefix*.
+ * Otherwise returns false.
+ */
+static int procfs_is_workload_pid(const char *workload_prefix, struct dirent *proc_entry)
+{
+ char comm_path[MAX_PATH], comm[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(comm_path, MAX_PATH, "/proc/%s/comm", proc_entry->d_name);
+ comm_fd = open(comm_path, O_RDONLY);
+ if (comm_fd < 0)
+ return 0;
+
+ memset(comm, 0, MAX_PATH);
+ retval = read(comm_fd, comm, MAX_PATH);
+
+ close(comm_fd);
+
+ if (retval <= 0)
+ return 0;
+
+ retval = !strncmp(workload_prefix, comm, strlen(workload_prefix));
+ if (!retval)
+ return 0;
+
+ /* comm already have \n */
+ debug_msg("Found workload pid:%s comm:%s", proc_entry->d_name, comm);
+
+ return 1;
+}
+
/*
* set_comm_sched_attr - set sched params to threads starting with char *comm
*
@@ -272,33 +328,26 @@ int __set_sched_attr(int pid, struct sched_attr *attr)
*/
int set_comm_sched_attr(const char *comm, 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;
- }
+ procfs = opendir("/proc");
- memset(&task, 0, sizeof(task));
+ while ((proc_entry = readdir(procfs))) {
- while (readproc(ptp, &task)) {
- retval = strncmp(comm, task.cmd, strlen(comm));
- if (retval)
+ retval = procfs_is_workload_pid(comm, proc_entry);
+ if (!retval)
continue;
- retval = __set_sched_attr(task.tid, attr);
+
+ /* procfs_is_workload_pid confirmed it is a pid */
+ retval = __set_sched_attr(atoi(proc_entry->d_name), attr);
if (retval)
goto out_err;
}
-
- closeproc(ptp);
return 0;
out_err:
- closeproc(ptp);
return 1;
}
diff --git a/tools/tracing/rtla/src/utils.h b/tools/tracing/rtla/src/utils.h
index fa08e374870a..4959a3e2c0d5 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); \
--
2.35.1
|