Re: [PATCH] proc: faster open/read/close with "permanent" files (fwd)
From: Julia Lawall
Date: Thu Feb 20 2020 - 09:48:01 EST
Hello,
It looks like an unlock may be needed o lines 721 and 732.
julia
---------- Forwarded message ----------
Hi Alexey,
I love your patch! Perhaps something to improve:
[auto build test WARNING on jeyu/modules-next]
[also build test WARNING on linus/master v5.6-rc2 next-20200218]
[cannot apply to linux/master]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]
url: https://github.com/0day-ci/linux/commits/Alexey-Dobriyan/proc-faster-open-read-close-with-permanent-files/20200218-231203
base: https://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux.git modules-next
:::::: branch date: 6 hours ago
:::::: commit date: 6 hours ago
If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@xxxxxxxxx>
Reported-by: Julia Lawall <julia.lawall@xxxxxxx>
>> fs/proc/generic.c:721:2-8: preceding lock on line 706
fs/proc/generic.c:732:4-10: preceding lock on line 706
fs/proc/generic.c:732:4-10: preceding lock on line 748
# https://github.com/0day-ci/linux/commit/3cd4ad42ca7c52d1513e7ba9f08a06197a7380c8
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout 3cd4ad42ca7c52d1513e7ba9f08a06197a7380c8
vim +721 fs/proc/generic.c
8ce584c7416d8a Al Viro 2013-03-30 699
8ce584c7416d8a Al Viro 2013-03-30 700 int remove_proc_subtree(const char *name, struct proc_dir_entry *parent)
8ce584c7416d8a Al Viro 2013-03-30 701 {
8ce584c7416d8a Al Viro 2013-03-30 702 struct proc_dir_entry *root = NULL, *de, *next;
8ce584c7416d8a Al Viro 2013-03-30 703 const char *fn = name;
8ce584c7416d8a Al Viro 2013-03-30 704 unsigned int len;
8ce584c7416d8a Al Viro 2013-03-30 705
ecf1a3dfff22bd Waiman Long 2015-09-09 @706 write_lock(&proc_subdir_lock);
8ce584c7416d8a Al Viro 2013-03-30 707 if (__xlate_proc_name(name, &parent, &fn) != 0) {
ecf1a3dfff22bd Waiman Long 2015-09-09 708 write_unlock(&proc_subdir_lock);
8ce584c7416d8a Al Viro 2013-03-30 709 return -ENOENT;
8ce584c7416d8a Al Viro 2013-03-30 710 }
8ce584c7416d8a Al Viro 2013-03-30 711 len = strlen(fn);
8ce584c7416d8a Al Viro 2013-03-30 712
710585d4922fd3 Nicolas Dichtel 2014-12-10 713 root = pde_subdir_find(parent, fn, len);
8ce584c7416d8a Al Viro 2013-03-30 714 if (!root) {
ecf1a3dfff22bd Waiman Long 2015-09-09 715 write_unlock(&proc_subdir_lock);
8ce584c7416d8a Al Viro 2013-03-30 716 return -ENOENT;
8ce584c7416d8a Al Viro 2013-03-30 717 }
3cd4ad42ca7c52 Alexey Dobriyan 2020-02-16 718 if (unlikely(pde_is_permanent(root))) {
3cd4ad42ca7c52 Alexey Dobriyan 2020-02-16 719 WARN(1, "removing permanent /proc entry '%s/%s'",
3cd4ad42ca7c52 Alexey Dobriyan 2020-02-16 720 root->parent->name, root->name);
3cd4ad42ca7c52 Alexey Dobriyan 2020-02-16 @721 return -EINVAL;
3cd4ad42ca7c52 Alexey Dobriyan 2020-02-16 722 }
4f1134370a29a5 Alexey Dobriyan 2018-04-10 723 rb_erase(&root->subdir_node, &parent->subdir);
710585d4922fd3 Nicolas Dichtel 2014-12-10 724
8ce584c7416d8a Al Viro 2013-03-30 725 de = root;
8ce584c7416d8a Al Viro 2013-03-30 726 while (1) {
710585d4922fd3 Nicolas Dichtel 2014-12-10 727 next = pde_subdir_first(de);
8ce584c7416d8a Al Viro 2013-03-30 728 if (next) {
3cd4ad42ca7c52 Alexey Dobriyan 2020-02-16 729 if (unlikely(pde_is_permanent(root))) {
3cd4ad42ca7c52 Alexey Dobriyan 2020-02-16 730 WARN(1, "removing permanent /proc entry '%s/%s'",
3cd4ad42ca7c52 Alexey Dobriyan 2020-02-16 731 next->parent->name, next->name);
3cd4ad42ca7c52 Alexey Dobriyan 2020-02-16 732 return -EINVAL;
3cd4ad42ca7c52 Alexey Dobriyan 2020-02-16 733 }
4f1134370a29a5 Alexey Dobriyan 2018-04-10 734 rb_erase(&next->subdir_node, &de->subdir);
8ce584c7416d8a Al Viro 2013-03-30 735 de = next;
8ce584c7416d8a Al Viro 2013-03-30 736 continue;
8ce584c7416d8a Al Viro 2013-03-30 737 }
8ce584c7416d8a Al Viro 2013-03-30 738 next = de->parent;
8ce584c7416d8a Al Viro 2013-03-30 739 if (S_ISDIR(de->mode))
8ce584c7416d8a Al Viro 2013-03-30 740 next->nlink--;
e06689bf57017a Alexey Dobriyan 2019-12-04 741 write_unlock(&proc_subdir_lock);
e06689bf57017a Alexey Dobriyan 2019-12-04 742
e06689bf57017a Alexey Dobriyan 2019-12-04 743 proc_entry_rundown(de);
8ce584c7416d8a Al Viro 2013-03-30 744 if (de == root)
8ce584c7416d8a Al Viro 2013-03-30 745 break;
8ce584c7416d8a Al Viro 2013-03-30 746 pde_put(de);
8ce584c7416d8a Al Viro 2013-03-30 747
ecf1a3dfff22bd Waiman Long 2015-09-09 748 write_lock(&proc_subdir_lock);
8ce584c7416d8a Al Viro 2013-03-30 749 de = next;
8ce584c7416d8a Al Viro 2013-03-30 750 }
8ce584c7416d8a Al Viro 2013-03-30 751 pde_put(root);
8ce584c7416d8a Al Viro 2013-03-30 752 return 0;
8ce584c7416d8a Al Viro 2013-03-30 753 }
8ce584c7416d8a Al Viro 2013-03-30 754 EXPORT_SYMBOL(remove_proc_subtree);
4a520d2769beb7 David Howells 2013-04-12 755
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