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Re: [patch] Fix for newer kernels with: t (tracing stop)
- From: Pedro Alves <palves at redhat dot com>
- To: Jan Kratochvil <jan dot kratochvil at redhat dot com>, gdb-patches at sourceware dot org
- Date: Fri, 22 Jul 2016 17:04:04 +0100
- Subject: Re: [patch] Fix for newer kernels with: t (tracing stop)
- Authentication-results: sourceware.org; auth=none
- References: <20160604122904.GA11651@host1.jankratochvil.net> <3132f4e9-8695-ad54-e0ef-c577dbdaba39@redhat.com>
On 07/22/2016 04:35 PM, Pedro Alves wrote:
> OK.
>
> I wonder whether it wouldn't simplify things to parse the
> state into some new enum lwp_state instead of the current scheme
> of passing state strings around. I may give that a try as follow up.
>
Like this. This one's against current master, however. Turned out to
be easy/quick to try. Untested though. I'll rebase if you want to put
yours in first.
>From 9be7dff19a73f6d64dcbb3d9cd7d965ca48c3ed6 Mon Sep 17 00:00:00 2001
From: Pedro Alves <palves@redhat.com>
Date: Fri, 22 Jul 2016 16:10:00 +0100
Subject: [PATCH] Introduce enum proc_state
---
gdb/nat/linux-procfs.c | 86 ++++++++++++++++++++++++++++++++++++++------------
1 file changed, 66 insertions(+), 20 deletions(-)
diff --git a/gdb/nat/linux-procfs.c b/gdb/nat/linux-procfs.c
index e2ea1d6..9dd3fd7 100644
--- a/gdb/nat/linux-procfs.c
+++ b/gdb/nat/linux-procfs.c
@@ -70,19 +70,67 @@ linux_proc_get_tracerpid_nowarn (pid_t lwpid)
return linux_proc_get_int (lwpid, "TracerPid", 0);
}
-/* Fill in BUFFER, a buffer with BUFFER_SIZE bytes with the 'State'
+/* Process states as discovered in the 'State' line of
+ /proc/PID/status. Not all possible states are represented here,
+ only those that we care about. */
+
+enum proc_state
+{
+ /* Some state we don't handle. */
+ PROC_STATE_UNKNOWN,
+
+ /* Stopped on a signal. */
+ PROC_STATE_STOPPED,
+
+ /* Tracing stop. */
+ PROC_STATE_TRACING_STOP,
+
+ /* Dead. */
+ PROC_STATE_DEAD,
+
+ /* Zombie. */
+ PROC_STATE_ZOMBIE,
+};
+
+/* Parse an PROC_STATE out of STATE, a buffer with the 'State' line of
+ /proc/PID/status. */
+
+static enum proc_state
+parse_proc_status_state (const char *state)
+{
+ switch (state[0])
+ {
+ case 't':
+ return PROC_STATE_TRACING_STOP;
+ case 'T':
+ /* Lowercase 't' was introduced in Linux 2.6.33. */
+ if (strcmp (state, "T (tracing stop)") == 0)
+ return PROC_STATE_TRACING_STOP;
+ else
+ return PROC_STATE_STOPPED;
+ case 'X':
+ return PROC_STATE_DEAD;
+ case 'Z':
+ return PROC_STATE_ZOMBIE;
+ }
+
+ return PROC_STATE_UNKNOWN;
+}
+
+
+/* Fill in STATE, a buffer with BUFFER_SIZE bytes with the 'State'
line of /proc/PID/status. Returns -1 on failure to open the /proc
file, 1 if the line is found, and 0 if not found. If WARN, warn on
failure to open the /proc file. */
static int
-linux_proc_pid_get_state (pid_t pid, char *buffer, size_t buffer_size,
- int warn)
+linux_proc_pid_get_state (pid_t pid, int warn, enum proc_state *state)
{
FILE *procfile;
int have_state;
+ char buffer[100];
- xsnprintf (buffer, buffer_size, "/proc/%d/status", (int) pid);
+ xsnprintf (buffer, sizeof buffer, "/proc/%d/status", (int) pid);
procfile = gdb_fopen_cloexec (buffer, "r");
if (procfile == NULL)
{
@@ -92,10 +140,11 @@ linux_proc_pid_get_state (pid_t pid, char *buffer, size_t buffer_size,
}
have_state = 0;
- while (fgets (buffer, buffer_size, procfile) != NULL)
+ while (fgets (buffer, sizeof (buffer), procfile) != NULL)
if (startswith (buffer, "State:"))
{
have_state = 1;
+ *state = parse_proc_status_state (buffer + sizeof ("State:") - 1);
break;
}
fclose (procfile);
@@ -107,10 +156,10 @@ linux_proc_pid_get_state (pid_t pid, char *buffer, size_t buffer_size,
int
linux_proc_pid_is_gone (pid_t pid)
{
- char buffer[100];
int have_state;
+ enum proc_state state;
- have_state = linux_proc_pid_get_state (pid, buffer, sizeof buffer, 0);
+ have_state = linux_proc_pid_get_state (pid, 0, &state);
if (have_state < 0)
{
/* If we can't open the status file, assume the thread has
@@ -123,41 +172,38 @@ linux_proc_pid_is_gone (pid_t pid)
return 0;
}
else
- {
- return (strstr (buffer, "Z (") != NULL
- || strstr (buffer, "X (") != NULL);
- }
+ return (state == PROC_STATE_ZOMBIE || state == PROC_STATE_DEAD);
}
/* Return non-zero if 'State' of /proc/PID/status contains STATE. If
WARN, warn on failure to open the /proc file. */
static int
-linux_proc_pid_has_state (pid_t pid, const char *state, int warn)
+linux_proc_pid_has_state (pid_t pid, enum proc_state state, int warn)
{
- char buffer[100];
int have_state;
+ enum proc_state cur_state;
- have_state = linux_proc_pid_get_state (pid, buffer, sizeof buffer, warn);
- return (have_state > 0 && strstr (buffer, state) != NULL);
+ have_state = linux_proc_pid_get_state (pid, warn, &cur_state);
+ return (have_state > 0 && cur_state == state);
}
/* Detect `T (stopped)' in `/proc/PID/status'.
- Other states including `T (tracing stop)' are reported as false. */
+ Other states including `t (tracing stop)' are reported as false. */
int
linux_proc_pid_is_stopped (pid_t pid)
{
- return linux_proc_pid_has_state (pid, "T (stopped)", 1);
+ return linux_proc_pid_has_state (pid, PROC_STATE_STOPPED, 1);
}
-/* Detect `T (tracing stop)' in `/proc/PID/status'.
+/* Detect `t (tracing stop)' in `/proc/PID/status'.
Other states including `T (stopped)' are reported as false. */
int
linux_proc_pid_is_trace_stopped_nowarn (pid_t pid)
{
- return linux_proc_pid_has_state (pid, "T (tracing stop)", 1);
+ return linux_proc_pid_has_state (pid, PROC_STATE_TRACING_STOP, 1);
}
/* Return non-zero if PID is a zombie. If WARN, warn on failure to
@@ -166,7 +212,7 @@ linux_proc_pid_is_trace_stopped_nowarn (pid_t pid)
static int
linux_proc_pid_is_zombie_maybe_warn (pid_t pid, int warn)
{
- return linux_proc_pid_has_state (pid, "Z (zombie)", warn);
+ return linux_proc_pid_has_state (pid, PROC_STATE_ZOMBIE, warn);
}
/* See linux-procfs.h declaration. */
--
2.5.5