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uprobes: Kill dup_mmap()->uprobe_mmap(), simplify uprobe_mmap/munmap 

1. Kill dup_mmap()->uprobe_mmap(), it was only needed to calculate
   new_mm->uprobes_state.count removed by the previous patch.

   If the forking process has a pending uprobe (int3) in vma, it will
   be copied by copy_page_range(), note that it checks vma->anon_vma
   so "Don't copy ptes" is not possible after install_breakpoint()
   which does anon_vma_prepare().

2. Remove is_swbp_at_addr() and "int count" in uprobe_mmap(). Again,
   this was needed for uprobes_state.count.

   As a side effect this fixes the bug pointed out by Srikar,
   this code lacked the necessary put_uprobe().

3. uprobe_munmap() becomes a nop after the previous patch. Remove the
   meaningless code but do not remove the helper, we will need it.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
hifive-unleashed-5.1
Oleg Nesterov 2012-08-06 14:13:23 +02:00
parent 647c42dfd4
commit f1a45d0231
2 changed files with 3 additions and 30 deletions
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30
kernel/events/uprobes.c
View File

@ -1010,7 +1010,7 @@ int uprobe_mmap(struct vm_area_struct *vma)
struct list_head tmp_list;
struct uprobe *uprobe, *u;
struct inode *inode;
int ret, count;
int ret;
if (!atomic_read(&uprobe_events) || !valid_vma(vma, true))
return 0;
@ -1023,8 +1023,6 @@ int uprobe_mmap(struct vm_area_struct *vma)
build_probe_list(inode, vma, vma->vm_start, vma->vm_end, &tmp_list);
ret = 0;
count = 0;
list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) {
if (!ret) {
unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset);
@ -1034,19 +1032,11 @@ int uprobe_mmap(struct vm_area_struct *vma)
* We can race against uprobe_register(), see the
* comment near uprobe_hash().
*/
if (ret == -EEXIST) {
if (ret == -EEXIST)
ret = 0;
if (!is_swbp_at_addr(vma->vm_mm, vaddr))
continue;
}
if (!ret)
count++;
}
put_uprobe(uprobe);
}
mutex_unlock(uprobes_mmap_hash(inode));
return ret;
@ -1057,27 +1047,13 @@ int uprobe_mmap(struct vm_area_struct *vma)
*/
void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end)
{
struct list_head tmp_list;
struct uprobe *uprobe, *u;
struct inode *inode;
if (!atomic_read(&uprobe_events) || !valid_vma(vma, false))
return;
if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */
return;
inode = vma->vm_file->f_mapping->host;
if (!inode)
return;
mutex_lock(uprobes_mmap_hash(inode));
build_probe_list(inode, vma, start, end, &tmp_list);
list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) {
put_uprobe(uprobe);
}
mutex_unlock(uprobes_mmap_hash(inode));
/* TODO: unmapping uprobe(s) will need more work */
}
/* Slot allocation for XOL */

3
kernel/fork.c
View File

@ -454,9 +454,6 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
if (retval)
goto out;
if (file)
uprobe_mmap(tmp);
}
/* a new mm has just been created */
arch_dup_mmap(oldmm, mm);