Re: [PATCH] task_work: remove fifo ordering guarantee

Eric Dumazet
2015-08-29T14:11:17Z

On Sat, 2015-08-29 at 06:57 -0700, Eric Dumazet wrote:

> Now we also could question why we needed commit
> 4a9d4b024a3102fc083c925c242d98ac27b1c5f6 ("switch fput to task_work_add
> ") since it seems quite an overhead at task exit with 10^6 of files to
> close.
>
> I understood the 'schedule_work() for interrupt/kernel_thread callers'
> part, but not the task_work_add() one.

If this needs to be kept, maybe then add following, to make sure
we flush the list at most every BITS_PER_LONG files

diff --git a/fs/file.c b/fs/file.c
index 6c672ad329e9..f3d0a79cef05 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -22,6 +22,7 @@
#include <linux/spinlock.h>
#include <linux/rcupdate.h>
#include <linux/workqueue.h>
+#include <linux/task_work.h>

int sysctl_nr_open __read_mostly = 1024*1024;
int sysctl_nr_open_min = BITS_PER_LONG;
@@ -392,6 +393,7 @@ static struct fdtable *close_files(struct
files_struct * files)
i++;
set >>= 1;
}
+ task_work_run();
}

return fdt;