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SubjectRe: [PATCH] task name handling in proc fs
On Thu, Jul 01, 2004 at 04:03:35PM -0700, Andrew Morton wrote:
>
> If we need locking around task->comm (and it seems that we do) then
> let's do it.
>
> void get_task_comm(char *buf, struct task_struct *tsk);
> void set_task_comm(struct task_struct *tsk, char *buf);
>
> It would be a bit lame to add a new lock for this - probably
> task_lock() could be coopted.

OK - Here is a patch to implement/use the routines above. I couldn't
decide on a good location (file) for them so I put them in 'fs/exec/c'
which is where the existing set_task_comm functionality resides. In
addition, I took the liberty of replacing the code in 'fs/proc/array.c'
that replicates the code in get_task_mm() with a simple call to the
routine.

--
Mike

diff -Naur linux-2.6.7/fs/exec.c linux-2.6.7.ptest2/fs/exec.c
--- linux-2.6.7/fs/exec.c Wed Jun 16 05:19:13 2004
+++ linux-2.6.7.ptest2/fs/exec.c Wed Jul 7 21:46:20 2004
@@ -786,10 +786,33 @@
spin_unlock(&files->file_lock);
}

+void get_task_comm(char *buf, struct task_struct *tsk)
+{
+ /* buf must be at least sizeof(tsk->comm) in size */
+ task_lock(tsk);
+ memcpy(buf, tsk->comm, sizeof(tsk->comm));
+ task_unlock(tsk);
+}
+
+void set_task_comm(struct task_struct *tsk, char *name)
+{
+ int i, ch;
+
+ task_lock(tsk);
+ for (i=0; (ch = *(name++)) != '\0';) {
+ if (ch == '/')
+ i = 0;
+ else
+ if (i < (sizeof(tsk->comm) - 1))
+ tsk->comm[i++] = ch;
+ }
+ tsk->comm[i] = '\0';
+ task_unlock(tsk);
+}
+
int flush_old_exec(struct linux_binprm * bprm)
{
- char * name;
- int i, ch, retval;
+ int retval;
struct files_struct *files;

/*
@@ -826,15 +849,8 @@

if (current->euid == current->uid && current->egid == current->gid)
current->mm->dumpable = 1;
- name = bprm->filename;
- for (i=0; (ch = *(name++)) != '\0';) {
- if (ch == '/')
- i = 0;
- else
- if (i < 15)
- current->comm[i++] = ch;
- }
- current->comm[i] = '\0';
+
+ set_task_comm(current, bprm->filename);

flush_thread();

diff -Naur linux-2.6.7/fs/proc/array.c linux-2.6.7.ptest2/fs/proc/array.c
--- linux-2.6.7/fs/proc/array.c Wed Jun 16 05:19:36 2004
+++ linux-2.6.7.ptest2/fs/proc/array.c Wed Jul 7 17:41:28 2004
@@ -88,10 +88,13 @@
{
int i;
char * name;
+ char tcomm[sizeof(p->comm)];
+
+ get_task_comm(tcomm, p);

ADDBUF(buf, "Name:\t");
- name = p->comm;
- i = sizeof(p->comm);
+ name = tcomm;
+ i = sizeof(tcomm);
do {
unsigned char c = *name;
name++;
@@ -308,14 +311,11 @@
int num_threads = 0;
struct mm_struct *mm;
unsigned long long start_time;
+ char tcomm[sizeof(task->comm)];

state = *get_task_state(task);
vsize = eip = esp = 0;
- task_lock(task);
- mm = task->mm;
- if(mm)
- mm = mmgrab(mm);
- task_unlock(task);
+ mm = get_task_mm(task);
if (mm) {
down_read(&mm->mmap_sem);
vsize = task_vsize(mm);
@@ -324,6 +324,7 @@
up_read(&mm->mmap_sem);
}

+ get_task_comm(tcomm, task);
wchan = get_wchan(task);

sigemptyset(&sigign);
@@ -361,7 +362,7 @@
%lu %lu %lu %lu %lu %ld %ld %ld %ld %d %ld %llu %lu %ld %lu %lu %lu %lu %lu \
%lu %lu %lu %lu %lu %lu %lu %lu %d %d %lu %lu\n",
task->pid,
- task->comm,
+ tcomm,
state,
ppid,
pgid,
diff -Naur linux-2.6.7/include/linux/sched.h linux-2.6.7.ptest2/include/linux/sched.h
--- linux-2.6.7/include/linux/sched.h Wed Jun 16 05:18:57 2004
+++ linux-2.6.7.ptest2/include/linux/sched.h Tue Jul 6 22:39:25 2004
@@ -868,6 +868,9 @@
extern long do_fork(unsigned long, unsigned long, struct pt_regs *, unsigned long, int __user *, int __user *);
extern struct task_struct * copy_process(unsigned long, unsigned long, struct pt_regs *, unsigned long, int __user *, int __user *);

+extern void set_task_comm(struct task_struct *, char *);
+extern void get_task_comm(char *, struct task_struct *);
+
#ifdef CONFIG_SMP
extern void wait_task_inactive(task_t * p);
#else
-
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