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RE: [PATCH][PR threads/15824] when get threads name failed from info threads with linux kernel version earlier than 2.6.33
- From: "Will Huang" <will dot huang at aliyun-inc dot com>
- To: "'Yao Qi'" <yao at codesourcery dot com>
- Cc: <gdb-patches at sourceware dot org>
- Date: Fri, 16 Aug 2013 18:22:04 +0800
- Subject: RE: [PATCH][PR threads/15824] when get threads name failed from info threads with linux kernel version earlier than 2.6.33
- References: <00b201ce98a6$7cf69150$76e3b3f0$ at huang@aliyun-inc.com> <520D8D9A dot 3050003 at codesourcery dot com> <016701ce9a41$f39086d0$dab19470$ at huang@aliyun-inc.com> <520DF2E2 dot 3020407 at codesourcery dot com>
Hello Qi,
Sorry for mistakes. There is no gdb_fopen_cloexec in gdb-7.6. Except that all comments are accepted.
Test OS:Linux 2.6.32-220.23.2.ali1089.el5.x86_64
GNU gdb (GDB) 7.6
Under linux kernel 2.6.32( or earlier version) there is no proc file named /proc/$pid/task/$tid/comm.
GDB init their threads' name from this proc file. So info threads can't print correct thread names when
This proc file not exist. This can be solve by using procfs /proc/$pid/task/$tid/status instead if comm file
not exists. Status file has a Name line which starts by "Name:".
diff -ruN ./gdb.org/ChangeLog ./gdb/ChangeLog
--- ./gdb.org/ChangeLog 2013-04-26 19:43:30.000000000 +0800
+++ ./gdb/ChangeLog 2013-08-16 17:47:39.000000000 +0800
@@ -1,3 +1,11 @@
+2013-08-14 Will Huang <will.huang@aliyun-inc.com>
+
+ PR threads/15824
+ * linux-nat.c (linux_nat_thread_name): Add get thread name from
+ procfs "/proc/$pid/task/$tid/status".
+ * commo/linux-procfs.c (linux_proc_get_thread_name): New.
+ (linux_proc_get_string): New.
+
2013-04-26 Joel Brobecker <brobecker@adacore.com>
* NEWS: Change "since GDB 7.5" into "in GDB 7.6".
diff -ruN ./gdb.org/common/linux-procfs.c ./gdb/common/linux-procfs.c
--- ./gdb.org/common/linux-procfs.c 2013-01-01 14:32:54.000000000 +0800
+++ ./gdb/common/linux-procfs.c 2013-08-16 17:51:44.000000000 +0800
@@ -55,6 +55,55 @@
return retval;
}
+/* Return the string length of FILED /proc/LWPID/task/TID/status.
+ Return -1 if not found. */
+
+static int
+linux_proc_get_string (pid_t lwpid, pid_t tid, char *target,
+ size_t t_size, const char *field)
+{
+ size_t field_len = strlen (field);
+ FILE *status_file;
+ char buf[100];
+ int retval = -1;
+
+ if (tid > 0)
+ xsnprintf (buf, sizeof (buf), "/proc/%d/task/%d/status",
+ (int) lwpid, (int) tid);
+ else
+ {
+ /*if TID is zero, ingnore it*/
+ xsnprintf (buf, sizeof (buf), "/proc/%d/status", (int) lwpid);
+ }
+
+ status_file = fopen (buf, "r");
+ if (status_file == NULL)
+ {
+ warning (_("unable to open /proc file '%s'"), buf);
+ return -1;
+ }
+
+ while (fgets (buf, sizeof (buf), status_file))
+ if (strncmp (buf, field, field_len) == 0 && buf[field_len] == ':')
+ {
+ size_t pos = field_len + 1;
+ while((buf[pos] == ' ' || buf[pos] == '\t')
+ && (pos < sizeof (buf) - 1))
+ pos++;
+
+ strncpy (target, &buf[pos], t_size);
+ target[t_size - 1] = '\0';
+ retval = strlen (target);
+ if (retval > 0 && target[retval - 1] == '\n')
+ target[retval - 1] = '\0';
+
+ break;
+ }
+
+ fclose (status_file);
+ return retval;
+}
+
/* Return the TGID of LWPID from /proc/pid/status. Returns -1 if not
found. */
@@ -118,3 +167,13 @@
{
return linux_proc_pid_has_state (pid, "Z (zombie)");
}
+
+/* Save the name of thread PID/TID into buffer NAME. SIZE is the size
+ of buffer NAME. Return the length of the name if success,
+ otherwise return -1. */
+
+int
+linux_proc_get_thread_name (pid_t pid, pid_t tid, char *name, size_t size)
+{
+ return linux_proc_get_string (pid, tid, name, size, "Name");
+}
diff -ruN ./gdb.org/common/linux-procfs.h ./gdb/common/linux-procfs.h
--- ./gdb.org/common/linux-procfs.h 2013-01-01 14:32:54.000000000 +0800
+++ ./gdb/common/linux-procfs.h 2013-08-16 11:48:49.000000000 +0800
@@ -40,4 +40,12 @@
extern int linux_proc_pid_is_zombie (pid_t pid);
+
+/* Save the name of thread PID/TID into buffer NAME. SIZE is the size
+ of buffer NAME. Return the length of the name if success,
+ otherwise return -1. */
+
+extern int linux_proc_get_thread_name (pid_t pid, pid_t tid,
+ char *name, size_t size);
+
#endif /* COMMON_LINUX_PROCFS_H */
diff -ruN ./gdb.org/linux-nat.c ./gdb/linux-nat.c
--- ./gdb.org/linux-nat.c 2013-02-13 22:59:49.000000000 +0800
+++ ./gdb/linux-nat.c 2013-08-16 17:55:19.000000000 +0800
@@ -4294,6 +4294,15 @@
fclose (comm_file);
}
+ else
+ {
+ static char comm[COMM_LEN + 1];
+ int size = linux_proc_get_thread_name ((pid_t) pid, (pid_t) lwp, comm, COMM_LEN + 1);
+
+ if (size > 0)
+ result = comm;
+
+ }
#undef COMM_LEN
#undef FORMAT
diff -ruN ./gdb.org/testsuite/ChangeLog ./gdb/testsuite/ChangeLog
--- ./gdb.org/testsuite/ChangeLog 2013-04-25 20:22:26.000000000 +0800
+++ ./gdb/testsuite/ChangeLog 2013-08-16 17:55:49.000000000 +0800
@@ -1,3 +1,9 @@
+2013-08-14 Will Huang <will.huang@aliyun-inc.com>
+
+ PR threads/15824
+ * gdb.threads/manythreads.exp: Add test for get thread
+ original name.
+
2013-04-25 Sergio Durigan Junior <sergiodj@redhat.com>
* gdb.arch/arm-bl-branch-dest.c: New file.
diff -ruN ./gdb.org/testsuite/gdb.threads/manythreads.exp ./gdb/testsuite/gdb.threads/manythreads.exp
--- ./gdb.org/testsuite/gdb.threads/manythreads.exp 2013-01-01 14:41:27.000000000 +0800
+++ ./gdb/testsuite/gdb.threads/manythreads.exp 2013-08-16 11:49:26.000000000 +0800
@@ -93,6 +93,7 @@
}
}
+gdb_test "info threads" ".*manythreads.*" "check thread original name"
gdb_test_no_output "thread name zardoz" "give a name to the thread"
gdb_test "info threads" ".*zardoz.*" "check thread name"
Thanks,
Will Huang
> -----Original Message-----
> From: Yao Qi [mailto:yao@codesourcery.com]
> Sent: Friday, August 16, 2013 5:38 PM
> To: Will Huang
> Cc: gdb-patches@sourceware.org
> Subject: Re: [PATCH][PR threads/15824] when get threads name failed from info
> threads with linux kernel version earlier than 2.6.33
>
> Will,
> not every comments are addressed by this updated patch. I'll point them out
> again. Please make sure your new patch will address all of them.
>
> On 08/16/2013 01:32 PM, Will Huang wrote:
> > +2013-08-14 Will Huang<will.huang@aliyun-inc.com>
> > +
> > + PR threads/15824
> ^^^^^^^
> Each line should be prefixed with 'TAB' instead of 8 spaces.
>
> > + * linux-nat.c (linux_nat_thread_name): Add get thread name from
> > + procfs "/proc/$pid/task/$tid/status".
> > + * commo/linux-procfs.c (linux_proc_get_thread_name
> > + linux_proc_get_string): New.
>
> People prefer to give one entry for one function separately, like:
>
> * commo/linux-procfs.c (linux_proc_get_thread_name): New
> function.
> (linux_proc_get_string): New function.
> > +
> > 2013-04-26 Joel Brobecker<brobecker@adacore.com>
> >
> > * NEWS: Change "since GDB 7.5" into "in GDB 7.6".
> > diff -uNr ./gdb.org/common/linux-procfs.c ./gdb/common/linux-procfs.c
> > --- ./gdb.org/common/linux-procfs.c 2013-01-01 14:32:54.000000000 +0800
> > +++ ./gdb/common/linux-procfs.c 2013-08-16 11:48:49.000000000 +0800
> > @@ -55,6 +55,55 @@
> > return retval;
> > }
> >
> > +/* Return the string length of FILED /proc/LWPID/task/TID/status.
> > + Return -1 if not found. */
> > +
> > +static int
> > +linux_proc_get_string (pid_t lwpid, pid_t tid, char *target,
> > + size_t t_size, const char *field) {
> > + size_t field_len = strlen (field);
> > + FILE *status_file;
> > + char buf[100];
> > + int retval = -1;
> > +
> > + if (tid > 0)
> > + snprintf (buf, sizeof (buf), "/proc/%d/task/%d/status",
> > + (int) lwpid, (int) tid);
>
> Use xsnprintf, and the indentation looks wrong.
>
> > + else
> > + {
> > + /*if TID is zero, ingnore it*/
> > + snprintf (buf, sizeof (buf), "/proc/%d/status", (int) lwpid);
> > + }
>
> and here....
>
> > +
> > + status_file = fopen (buf, "r");
>
> Use gdb_fopen_cloexec?
>
> > + if (status_file == NULL)
> > + {
> > + warning (_("unable to open /proc file '%s'"), buf);
> > + return -1;
> > + }
> > +
> > + while (fgets (buf, sizeof (buf), status_file))
> > + if (strncmp (buf, field, field_len) == 0 && buf[field_len] == ':')
> > + {
> > + size_t pos = field_len + 1;
> > + while((buf[pos] == ' ' || buf[pos] == '\t')
> > + && (pos < sizeof (buf) - 1))
>
> Wrong indentation.
>
> > + pos++;
> > +
> > + strncpy (target, &buf[pos], t_size);
> > + target[t_size - 1] = '\0';
> > + retval = strlen (target);
> > + if(retval > 0 && target[retval - 1] == '\n')
> > + target[retval - 1] = '\0';
>
> Wrong indentation.
>
>
> > diff -uNr ./gdb.org/linux-nat.c ./gdb/linux-nat.c
> > --- ./gdb.org/linux-nat.c 2013-02-13 22:59:49.000000000 +0800
> > +++ ./gdb/linux-nat.c 2013-08-16 13:22:31.000000000 +0800
> > @@ -4294,6 +4294,14 @@
> >
> > fclose (comm_file);
> > }
> > + else
> > + {
> > + static char comm[COMM_LEN + 1];
> > + int size = linux_proc_get_thread_name (pid, lwp, comm, COMM_LEN
> > + + 1);
>
> A blank line is needed.
>
> The type of pid is int and type of lwp is long, but the types of parameters of
> linux_proc_get_thread_name are pid_t and pid_t. It is inconsistent.
>
> > + if (size > 0)
> > + result = comm;
> > +
> > + }
> >
> > #undef COMM_LEN
> > #undef FORMAT
> > diff -uNr ./gdb.org/testsuite/ChangeLog ./gdb/testsuite/ChangeLog
> > --- ./gdb.org/testsuite/ChangeLog 2013-04-25 20:22:26.000000000 +0800
> > +++ ./gdb/testsuite/ChangeLog 2013-08-16 11:49:02.000000000 +0800
> > @@ -1,3 +1,9 @@
> > +2013-08-14 Will Huang<will.huang@aliyun-inc.com>
> > +
> > + PR threads/15824
> > + * gdb.threads/manythreads.exp: Add test for get thread
> > + original name
>
> Period is missing.
>
> --
> Yao (éå)