Messages in this thread | | | Date | Mon, 5 Mar 2012 16:28:26 +0100 | From | Oleg Nesterov <> | Subject | [PATCH 0/1] turn mm->exe_file into mm->exe_path |
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I think the patch is simple and self-explanatory, it simply does s/mm->exe_file/mm->exe_path/.
Why do we need mm->exe_file? IIUC, there are 2 reasons:
1. we do not want O(n) proc/pid/exe looking for the 1st VM_EXECUTABLE vma.
2. we do not want to rely on vma->vm_file->f_path, bprm->file->f_op->mmap can change ->vm_file.
Unless there was another subtle reason, "struct path *exe_path" can equally work but it looks more clear.
And can't we also remove added_exe_file_vma/removed_exe_file_vma? Why do we need mm->num_exe_file_vmas? Afaics it is only needed to "free" mm->exe_file if the application unmaps all these vmas. Say, to allow to unmount fs.
Can't we simply add PR_CLEAR_MM_EXE_PATH instead? Of course it is not enough if ->vm_file still has a reference. But c/r people want PR_SET_MM_EXE_FILE anyway, see http://marc.info/?t=133052865500016 So perhaps we can add PR_SET_MM_EXE_PATH which accepts NULL as well and kill this counter?
Oleg.
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