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From:   Deepa Dinamani <deepa.kernel@gmail.com>
Date:   Thu, 23 May 2019 14:06:45 -0700
Message-ID: <CABeXuvrKAz3epJjc9J21K-dET1Om9C=3gaDOUiQ96C39x4MAVg@mail.gmail.com>
Subject: Re: [PATCH v2] signal: Adjust error codes according to restore_user_sigmask()
To:     David Laight <David.Laight@aculab.com>
Cc:     Oleg Nesterov <oleg@redhat.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Arnd Bergmann <arnd@arndb.de>,
        "dbueso@suse.de" <dbueso@suse.de>,
        "axboe@kernel.dk" <axboe@kernel.dk>,
        Davidlohr Bueso <dave@stgolabs.net>, Eric Wong <e@80x24.org>,
        Jason Baron <jbaron@akamai.com>,
        Linux FS-devel Mailing List <linux-fsdevel@vger.kernel.org>,
        linux-aio <linux-aio@kvack.org>,
        Omar Kilani <omar.kilani@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>
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> Just adding a little more clarification, there is an additional change
> between [a] and [b].
> As per [a] we would just restore the signal instead of changing the
> saved_sigmask and the signal could get delivered right then. [b]
> changes this to happen at syscall exit:

Rewording above, as there seems to be a few misrepresentations:

Just adding a little more clarification, there is an additional change
between [a] and [b].
As per [a] we would just restore the signal mask instead of changing
the saved_sigmask and the even the blocked signals could get delivered
right then. [b] changes the restoration to happen at syscall exit:

> void restore_user_sigmask(const void __user *usigmask, sigset_t *sigsaved)
> {
>
>            <snip>
>
>           /*
>            * When signals are pending, do not restore them here.
>            * Restoring sigmask here can lead to delivering signals
> that the above
>            * syscalls are intended to block because of the sigmask passed in.
>            */
>            if (signal_pending(current)) {
>            current->saved_sigmask = *sigsaved;
>            set_restore_sigmask();
>            return;
> }

 -Deepa