Re: [PATCH] [5/6] Handle TIF_RESTORE_SIGMASK for i386

From: Andrew Morton
Date: Thu Jan 12 2006 - 22:59:00 EST


David Woodhouse <dwmw2@xxxxxxxxxxxxx> wrote:
>
> The attached patch handles TIF_RESTORE_SIGMASK as added by David Woodhouse's
> patch entitled:
>
> [PATCH] 2/3 Add TIF_RESTORE_SIGMASK support for arch/powerpc
> [PATCH] 3/3 Generic sys_rt_sigsuspend
>
> It does the following:
>
> (1) Declares TIF_RESTORE_SIGMASK for i386.
>
> (2) Invokes it over to do_signal() when TIF_RESTORE_SIGMASK is set.
>
> (3) Makes do_signal() support TIF_RESTORE_SIGMASK, using the signal mask saved
> in current->saved_sigmask.
>
> (4) Discards sys_rt_sigsuspend() from the arch, using the generic one instead.
>
> (5) Makes sys_sigsuspend() save the signal mask and set TIF_RESTORE_SIGMASK
> rather than attempting to fudge the return registers.
>
> (6) Makes sys_sigsuspend() return -ERESTARTNOHAND rather than looping
> intrinsically.
>
> (7) Makes setup_frame(), setup_rt_frame() and handle_signal() return 0 or
> -EFAULT rather than true/false to be consistent with the rest of the
> kernel.
>
> Due to the fact do_signal() is then only called from one place:
>
> (8) Makes do_signal() no longer have a return value is it was just being
> ignored; force_sig() takes care of this.
>
> (9) Discards the old sigmask argument to do_signal() as it's no longer
> necessary.
>
> (10) Makes do_signal() static.
>
> (11) Marks the second argument to do_notify_resume() as unused. The unused
> argument should remain in the middle as the arguments are passed in as
> registers, and the ordering is specific in entry.S
>
> Given the way do_signal() is now no longer called from sys_{,rt_}sigsuspend(),
> they no longer need access to the exception frame, and so can just take
> arguments normally.
>
> This patch depends on sys_rt_sigsuspend patch.

I have problems with this patch.

With

generic-sys_rt_sigsuspend.patch
handle-tif_restore_sigmask-for-frv.patch
handle-tif_restore_sigmask-for-i386.patch

applied, or with all of David's patches applied, an FC5-test1 machine hangs
during the login process (local vt or sshd). An FC1 machine doesn't
exhibit the problem.

dmesg+sysrq-t:
http://www.zip.com.au/~akpm/linux/patches/stuff/dmesg

.config:
http://www.zip.com.au/~akpm/linux/patches/stuff/config-sony

culprit patches:
http://www.zip.com.au/~akpm/linux/patches/stuff/generic-sys_rt_sigsuspend.patch
http://www.zip.com.au/~akpm/linux/patches/stuff/handle-tif_restore_sigmask-for-i386.patch

(I retested with just current -linus and the above two patches. Same
deal).

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