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Subject[RFC PATCH 3/5] signal: Always keep real_blocked in sync with blocked

Except where we temporarily override blocked always keep real_blocked
in sync with blocked.

By always setting real_blocked when we set blocked this allows
some slight efficiency and simplifications, by not having
to save blocked.

This also preparse the code for the removal of saved_sigmask. That
should result in a massive simplification.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
kernel/ptrace.c | 1 +
kernel/signal.c | 14 ++++++++++----
virt/kvm/kvm_main.c | 8 --------
3 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 6f357f4fc859..6507d700d70f 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -968,6 +968,7 @@ int ptrace_request(struct task_struct *child, long request,
*/
spin_lock_irq(&child->sighand->siglock);
child->blocked = new_set;
+ child->real_blocked = new_set;
spin_unlock_irq(&child->sighand->siglock);

clear_tsk_restore_sigmask(child);
diff --git a/kernel/signal.c b/kernel/signal.c
index bfa36320a4f7..fcd84f4a93c9 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2878,6 +2878,9 @@ void set_current_blocked(sigset_t *newset)
{
sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
__set_current_blocked(newset);
+
+ /* Lockless, only current can change ->real_blocked, never from irq */
+ current->real_blocked = *newset;
}

void __set_current_blocked(const sigset_t *newset)
@@ -2928,15 +2931,20 @@ int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
}

__set_current_blocked(&newset);
+
+ /* Lockless, only current can change ->real_blocked, never from irq */
+ tsk->real_blocked = newset;
return 0;
}
EXPORT_SYMBOL(sigprocmask);

-static int set_sigmask(sigset_t *kmask)
+static int set_sigmask(sigset_t *newset)
{
set_restore_sigmask();
current->saved_sigmask = current->blocked;
- set_current_blocked(kmask);
+
+ sigdelsetmask(newset, sigmask(SIGKILL) | sigmask(SIGSTOP));
+ __set_current_blocked(newset);

return 0;
}
@@ -3440,7 +3448,6 @@ static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info,
* they arrive. Unblocking is always fine, we can avoid
* set_current_blocked().
*/
- tsk->real_blocked = tsk->blocked;
sigandsets(&tsk->blocked, &tsk->blocked, &mask);
recalc_sigpending();
spin_unlock_irq(&tsk->sighand->siglock);
@@ -3450,7 +3457,6 @@ static int do_sigtimedwait(const sigset_t *which, kernel_siginfo_t *info,
HRTIMER_MODE_REL);
spin_lock_irq(&tsk->sighand->siglock);
__set_task_blocked(tsk, &tsk->real_blocked);
- sigemptyset(&tsk->real_blocked);
sig = dequeue_signal(tsk, &mask, info);
}
spin_unlock_irq(&tsk->sighand->siglock);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 8575a1010bfc..4bfed018574a 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2234,13 +2234,6 @@ void kvm_sigset_activate(struct kvm_vcpu *vcpu)
if (!vcpu->sigset_active)
return;

- /*
- * This does a lockless modification of ->real_blocked, which is fine
- * because, only current can change ->real_blocked and all readers of
- * ->real_blocked don't care as long ->real_blocked is always a subset
- * of ->blocked.
- */
- current->real_blocked = current->blocked;
__set_current_blocked(&vcpu->sigset);
}

@@ -2250,7 +2243,6 @@ void kvm_sigset_deactivate(struct kvm_vcpu *vcpu)
return;

__set_current_blocked(&current->real_blocked);
- sigemptyset(&current->real_blocked);
}

static void grow_halt_poll_ns(struct kvm_vcpu *vcpu)
--
2.21.0.dirty
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