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Subject[PATCH] consolidate task->mm code + fix

The patch below consolidates some duplicate code, reduces some indentation, and
adds a freeing of a page in mem_read() that could left unfreed, as far as I can
see.

against 2.5.25

thanks
john


Index: fs/proc/array.c
===================================================================
RCS file: /old/linux-2.5/cvs/linux/fs/proc/array.c,v
retrieving revision 1.1.1.1
diff -u -r1.1.1.1 array.c
--- fs/proc/array.c 2002/07/15 01:40:22 1.1.1.1
+++ fs/proc/array.c 2002/07/15 18:22:25
@@ -277,15 +277,11 @@
int proc_pid_status(struct task_struct *task, char * buffer)
{
char * orig = buffer;
- struct mm_struct *mm;
+ struct mm_struct *mm = get_task_mm(task);

buffer = task_name(task, buffer);
buffer = task_state(task, buffer);
- task_lock(task);
- mm = task->mm;
- if(mm)
- atomic_inc(&mm->mm_users);
- task_unlock(task);
+
if (mm) {
buffer = task_mem(mm, buffer);
mmput(mm);
@@ -481,14 +477,9 @@

int proc_pid_statm(struct task_struct *task, char * buffer)
{
- struct mm_struct *mm;
int size=0, resident=0, share=0, trs=0, lrs=0, drs=0, dt=0;
+ struct mm_struct *mm = get_task_mm(task);

- task_lock(task);
- mm = task->mm;
- if(mm)
- atomic_inc(&mm->mm_users);
- task_unlock(task);
if (mm) {
struct vm_area_struct * vma;
down_read(&mm->mmap_sem);
@@ -626,11 +617,8 @@
if (!tmp)
goto out_free1;

- task_lock(task);
- mm = task->mm;
- if (mm)
- atomic_inc(&mm->mm_users);
- task_unlock(task);
+ mm = get_task_mm(task);
+
retval = 0;
if (!mm)
goto out_free2;
Index: fs/proc/base.c
===================================================================
RCS file: /old/linux-2.5/cvs/linux/fs/proc/base.c,v
retrieving revision 1.1.1.1
diff -u -r1.1.1.1 base.c
--- fs/proc/base.c 2002/07/15 01:40:22 1.1.1.1
+++ fs/proc/base.c 2002/07/15 19:40:31
@@ -131,16 +131,11 @@

static int proc_exe_link(struct inode *inode, struct dentry **dentry, struct vfsmount **mnt)
{
- struct mm_struct * mm;
struct vm_area_struct * vma;
int result = -ENOENT;
struct task_struct *task = proc_task(inode);
+ struct mm_struct * mm = get_task_mm(task);

- task_lock(task);
- mm = task->mm;
- if (mm)
- atomic_inc(&mm->mm_users);
- task_unlock(task);
if (!mm)
goto out;
down_read(&mm->mmap_sem);
@@ -203,13 +198,8 @@

static int proc_pid_environ(struct task_struct *task, char * buffer)
{
- struct mm_struct *mm;
int res = 0;
- task_lock(task);
- mm = task->mm;
- if (mm)
- atomic_inc(&mm->mm_users);
- task_unlock(task);
+ struct mm_struct *mm = get_task_mm(task);
if (mm) {
int len = mm->env_end - mm->env_start;
if (len > PAGE_SIZE)
@@ -222,38 +212,39 @@

static int proc_pid_cmdline(struct task_struct *task, char * buffer)
{
- struct mm_struct *mm;
int res = 0;
- task_lock(task);
- mm = task->mm;
- if (mm)
- atomic_inc(&mm->mm_users);
- task_unlock(task);
- if (mm) {
- int len = mm->arg_end - mm->arg_start;
- if (len > PAGE_SIZE)
- len = PAGE_SIZE;
- res = access_process_vm(task, mm->arg_start, buffer, len, 0);
- // If the nul at the end of args has been overwritten, then
- // assume application is using setproctitle(3).
- if ( res > 0 && buffer[res-1] != '\0' )
+ int len;
+ struct mm_struct *mm = get_task_mm(task);
+ if (!mm)
+ goto out;
+
+ len = mm->arg_end - mm->arg_start;
+
+ if (len > PAGE_SIZE)
+ len = PAGE_SIZE;
+
+ res = access_process_vm(task, mm->arg_start, buffer, len, 0);
+ // If the nul at the end of args has been overwritten, then
+ // assume application is using setproctitle(3).
+ if ( res > 0 && buffer[res-1] != '\0' )
+ {
+ len = strnlen( buffer, res );
+ if ( len < res )
{
- len = strnlen( buffer, res );
- if ( len < res )
- {
- res = len;
- }
- else
- {
- len = mm->env_end - mm->env_start;
- if (len > PAGE_SIZE - res)
- len = PAGE_SIZE - res;
- res += access_process_vm(task, mm->env_start, buffer+res, len, 0);
- res = strnlen( buffer, res );
- }
+ res = len;
}
- mmput(mm);
+ else
+ {
+ len = mm->env_end - mm->env_start;
+ if (len > PAGE_SIZE - res)
+ len = PAGE_SIZE - res;
+ res += access_process_vm(task, mm->env_start, buffer+res, len, 0);
+ res = strnlen( buffer, res );
+ }
}
+ mmput(mm);
+
+out:
return res;
}

@@ -421,54 +412,59 @@
struct task_struct *task = proc_task(file->f_dentry->d_inode);
char *page;
unsigned long src = *ppos;
- int copied = 0;
+ int ret = -ESRCH;
struct mm_struct *mm;

-
if (!MAY_PTRACE(task))
- return -ESRCH;
+ goto out;

+ ret = -ENOMEM;
page = (char *)__get_free_page(GFP_USER);
if (!page)
- return -ENOMEM;
+ goto out;

- task_lock(task);
- mm = task->mm;
- if (mm)
- atomic_inc(&mm->mm_users);
- task_unlock(task);
+ ret = 0;
+
+ mm = get_task_mm(task);
if (!mm)
- return 0;
+ goto out_free;

- if (file->private_data != (void*)((long)current->self_exec_id) ) {
- mmput(mm);
- return -EIO;
- }
-
+ ret = -EIO;
+
+ if (file->private_data != (void*)((long)current->self_exec_id))
+ goto out_put;

+ ret = 0;
+
while (count > 0) {
int this_len, retval;

this_len = (count > PAGE_SIZE) ? PAGE_SIZE : count;
retval = access_process_vm(task, src, page, this_len, 0);
if (!retval) {
- if (!copied)
- copied = -EIO;
+ if (!ret)
+ ret = -EIO;
break;
}
+
if (copy_to_user(buf, page, retval)) {
- copied = -EFAULT;
+ ret = -EFAULT;
break;
}
- copied += retval;
+
+ ret += retval;
src += retval;
buf += retval;
count -= retval;
}
*ppos = src;
+
+out_put:
mmput(mm);
+out_free:
free_page((unsigned long) page);
- return copied;
+out:
+ return ret;
}

#define mem_write NULL
Index: include/linux/sched.h
===================================================================
RCS file: /old/linux-2.5/cvs/linux/include/linux/sched.h,v
retrieving revision 1.1.1.1
diff -u -r1.1.1.1 sched.h
--- include/linux/sched.h 2002/07/15 01:40:11 1.1.1.1
+++ include/linux/sched.h 2002/07/15 19:10:36
@@ -787,6 +787,27 @@
return res;
}

+
+/**
+ * get_task_mm - acquire a reference to the task's mm
+ *
+ * Returns %NULL if the task has no mm. User must release
+ * the mm via mmput() after use.
+ */
+static inline struct mm_struct * get_task_mm(struct task_struct * task)
+{
+ struct mm_struct * mm;
+
+ task_lock(task);
+ mm = task->mm;
+ if (mm)
+ atomic_inc(&mm->mm_users);
+ task_unlock(task);
+
+ return mm;
+}
+
+
/* set thread flags in other task's structures
* - see asm/thread_info.h for TIF_xxxx flags available
*/
Index: kernel/ptrace.c
===================================================================
RCS file: /old/linux-2.5/cvs/linux/kernel/ptrace.c,v
retrieving revision 1.1.1.1
diff -u -r1.1.1.1 ptrace.c
--- kernel/ptrace.c 2002/07/15 01:40:24 1.1.1.1
+++ kernel/ptrace.c 2002/07/15 19:07:54
@@ -120,12 +120,7 @@
struct page *page;
void *old_buf = buf;

- /* Worry about races with exit() */
- task_lock(tsk);
- mm = tsk->mm;
- if (mm)
- atomic_inc(&mm->mm_users);
- task_unlock(tsk);
+ mm = get_task_mm(tsk);
if (!mm)
return 0;

-
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