From: ebiederm@xmission.com (Eric W. Biederman)
To: Jeff Layton <jlayton@kernel.org>
Cc: viro@zeniv.linux.org.uk, berrange@redhat.com,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
Oleg Nesterov <oleg@redhat.com>
Subject: [RFC][PATCH 0/3] exec: Moving unshare_files_struct
Date: Sun, 16 Sep 2018 19:38:55 +0200 [thread overview]
Message-ID: <87a7ohs5ow.fsf@xmission.com> (raw)
In-Reply-To: <20180914105310.6454-1-jlayton@kernel.org> (Jeff Layton's message of "Fri, 14 Sep 2018 06:53:07 -0400")
Paired with Oleg's patch to reduce the number of callers of
get_files_struct it looks like we can simplify the basic idea of moving
unshare_files in exec by quite a bit so that in net we have fewer lines
of code.
The big simplification from Jeff's verion is that we take advantage
of calling unshare_files past the point of no return. Which removes
the need for cleanup, and restoring ->files. Which removes the
need for blocking clone and unshare.
Oleg's patch to remove get_files_struct from proc means we don't need
two counts in files_struct.
Which leaves us with the question of what are the races in fs/exec.c
with respect to accessing files. Semantically I don't think we care
but we do need to be certain the implementation of exec is still robust.
These patches are still rough and ready and only compile tested but I
believe they demonstrate what is possible.
Eric W. Biederman (3):
exec: Move unshare_files down to avoid locks being dropped on exec.
exec: Simplify unshare_files
exec: Remove reset_files_struct
fs/coredump.c | 5 +----
fs/exec.c | 16 +++++-----------
fs/file.c | 12 ------------
include/linux/fdtable.h | 3 +--
kernel/fork.c | 12 ++++++------
5 files changed, 13 insertions(+), 35 deletions(-)
Eric
next prev parent reply other threads:[~2018-09-16 17:38 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-14 10:53 [PATCH v3 0/3] exec: fix passing of file locks across execve in multithreaded processes Jeff Layton
2018-09-14 10:53 ` [PATCH v3 1/3] exec: separate thread_count for files_struct Jeff Layton
2018-09-15 16:04 ` Oleg Nesterov
2018-09-16 16:10 ` Eric W. Biederman
2018-09-17 15:24 ` Oleg Nesterov
2018-09-17 20:45 ` Eric W. Biederman
2018-09-14 10:53 ` [PATCH v3 2/3] exec: delay clone(CLONE_FILES) if task associated with current files_struct is exec'ing Jeff Layton
2018-09-14 10:53 ` [PATCH v3 3/3] exec: do unshare_files after de_thread Jeff Layton
2018-09-15 16:37 ` Oleg Nesterov
2018-09-16 16:49 ` Eric W. Biederman
2018-09-17 15:28 ` Oleg Nesterov
2018-09-16 16:59 ` Eric W. Biederman
2018-09-16 17:38 ` Eric W. Biederman [this message]
2018-09-16 17:39 ` [RFC][PATCH 1/3] exec: Move unshare_files down to avoid locks being dropped on exec Eric W. Biederman
2018-09-17 15:49 ` Oleg Nesterov
2018-09-16 17:40 ` [RFC][PATCH 2/3] exec: Simplify unshare_files Eric W. Biederman
2018-09-17 16:23 ` Oleg Nesterov
2018-09-17 20:26 ` Eric W. Biederman
2018-09-16 17:41 ` [RFC][PATCH 3/3] exec: Remove reset_files_struct Eric W. Biederman
2018-09-17 15:59 ` [RFC][PATCH 0/3] exec: Moving unshare_files_struct Oleg Nesterov
2018-09-18 22:18 ` Eric W. Biederman
2018-09-17 16:24 ` Jeff Layton
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