linux-kernel - [RFC PATCH 0/5]: Removing saved

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Date:   Fri, 07 Jun 2019 16:39:54 -0500
From:   ebiederm@...ssion.com (Eric W. Biederman)
To:     Oleg Nesterov <oleg@...hat.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Deepa Dinamani <deepa.kernel@...il.com>,
        linux-kernel@...r.kernel.org, arnd@...db.de, dbueso@...e.de,
        axboe@...nel.dk, dave@...olabs.net, e@...24.org, jbaron@...mai.com,
        linux-fsdevel@...r.kernel.org, linux-aio@...ck.org,
        omar.kilani@...il.com, tglx@...utronix.de, stable@...r.kernel.org,
        Al Viro <viro@...IV.linux.org.uk>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        David Laight <David.Laight@...LAB.COM>,
        <linux-arch@...r.kernel.org>
Subject: [RFC PATCH 0/5]: Removing saved_sigmask


While reviewing Oleg's patches I realized a bunch of the logic around
saved_sigmask was redundant.  So I dug just to see what I could see.

I turns out that real_blocked and saved_sigmask were different
implementations of the same idea for slightly different purposes.
Which means we only need either real_blocked or saved_sigmask.

I chose real_blocked as it has just a little bit of code associated
with it to disable optimizations on the signal sending path that do
not apply to blocked signals.

I did a little bit of cleanup of the users.  Modified the core to keep
real_blocked in sync with blocked except while a clever system call that
like pselect or sigtimedwait is running.

After the dust cleared this allowed restore_sigmask and all of the logic
to keep it valid to be removed entirely.

I have only done the most cursory of testing at this point.  Does anyone
have any thoughts in cleaning up the code in this direction?

Eric W. Biederman (5):
      signal: Teach sigsuspend to use set_user_sigmask
      signal/kvm:  Stop using sigprocmask in kvm_sigset_(activate|deactivate)
      signal: Always keep real_blocked in sync with blocked
      signal: Remove saved_sigmask
      signal: Remove the unnecessary restore_sigmask flag

 arch/arc/include/asm/thread_info.h       |  1 -
 arch/arm/include/asm/thread_info.h       |  1 -
 arch/arm64/include/asm/thread_info.h     |  1 -
 arch/c6x/include/asm/thread_info.h       |  1 -
 arch/csky/include/asm/thread_info.h      |  2 -
 arch/h8300/include/asm/thread_info.h     |  1 -
 arch/hexagon/include/asm/thread_info.h   |  1 -
 arch/m68k/include/asm/thread_info.h      |  1 -
 arch/mips/include/asm/thread_info.h      |  1 -
 arch/nds32/include/asm/thread_info.h     |  2 -
 arch/nios2/include/asm/thread_info.h     |  2 -
 arch/riscv/include/asm/thread_info.h     |  1 -
 arch/s390/include/asm/thread_info.h      |  1 -
 arch/sparc/include/asm/thread_info_32.h  |  1 -
 arch/um/include/asm/thread_info.h        |  1 -
 arch/unicore32/include/asm/thread_info.h |  1 -
 arch/xtensa/include/asm/thread_info.h    |  1 -
 include/linux/sched.h                    |  5 --
 include/linux/sched/signal.h             | 84 +-------------------------------
 kernel/ptrace.c                          | 15 ++----
 kernel/signal.c                          | 56 +++++++++------------
 virt/kvm/kvm_main.c                      | 11 +----
 22 files changed, 31 insertions(+), 160 deletions(-)

Eric