[PATCH -part1 0/3] mm: improve handling of mm->exe_file

Davidlohr Bueso
2015-02-19T00:10:51Z

From: Davidlohr Bueso <dave@stgolabs.net>

This series is the first in a few where I'm planning on removing
the mmap_sem need for exe_file serialization. This is absurd and
needs to have its own locking. Anyway, this is the final goal, and
this series is just the first of a few that deals with unifying users
of exe_file.

For now we only deal with audit and tomoyo, the most obvious naughty
users, which only take the mmap_sem for exe_file. Over the years,
relying on the mmap_sem for exe_file has made some callers increasingly
messy and it is not as straightforward.

Essentially, we want to convert:

down_read(&mm->mmap_sem);
do_something_with(mm->exe_file);
up_read(&mm->mmap_sem);

to:

exe_file = get_mm_exe_file(mm); <--- mmap_sem is only held here.
do_something_with(mm->exe_file);
fput(exe_file);

On its own, these patches already have value in that we reduce mmap_sem hold
times and critical region. Once all users are standardized, converting the
lock rules will be much easier.

Thanks!

Davidlohr Bueso (3):
kernel/audit: consolidate handling of mm->exe_file
kernel/audit: robustify handling of mm->exe_file
security/tomoyo: robustify handling of mm->exe_file

kernel/audit.c | 9 +--------
kernel/audit.h | 20 ++++++++++++++++++++
kernel/auditsc.c | 9 +--------
security/tomoyo/common.c | 41 ++++++++++++++++++++++++++++++++++++++---
security/tomoyo/common.h | 1 -
security/tomoyo/util.c | 22 ----------------------
6 files changed, 60 insertions(+), 42 deletions(-)

--
2.1.4