Re: [PATCH 20/40] mn10300: Use set_current_blocked() and block_sigmask()

From: Matt Fleming <hidden>
Date: 2012-02-14 17:59:48
Also in: lkml
Reply to: David Howells, 2012-02-14

On Tue, 2012-02-14 at 15:56 +0000, David Howells wrote:

Matt Fleming [off-list ref] wrote:

quoted

 asmlinkage long sys_sigsuspend(int history0, int history1, old_sigset_t mask)
 {
-	mask &= _BLOCKABLE;
-	spin_lock_irq(&current->sighand->siglock);
+	sigset_t blocked;
+
 	current->saved_sigmask = current->blocked;

Can this line create a race, now that it's not protected by a lock?  It is
possible for current->blocked to get altered by another thread.

->blocked can only ever be altered by current, not another thread. See
the following comment from sigprocmask() in kernel/signal.c,

       /* Lockless, only current can change ->blocked, never from irq */
        if (oldset)                                                                                      
                *oldset = tsk->blocked;                                                                  

-- 
Matt Fleming, Intel Open Source Technology Center

Matt Fleming · 2012-02-14
[PATCH 02/40] arm: Use set_current_blocked() and block_sigmask() · Matt Fleming · 2012-02-14
[PATCH 01/40] alpha: Use set_current_blocked() and block_sigmask() · Matt Fleming · 2012-02-14
[PATCH 03/40] avr32: Don't mask signals in the error path · Matt Fleming · 2012-02-14
[PATCH 04/40] avr32: use set_current_blocked() in handle_signal/sys_rt_sigreturn · Matt Fleming · 2012-02-14
[PATCH 05/40] avr32: Use block_sigmask() · Matt Fleming · 2012-02-14
[PATCH 06/40] blackfin: Use set_current_blocked() and block_sigmask() · Matt Fleming · 2012-02-14
Re: [PATCH 06/40] blackfin: Use set_current_blocked() and block_sigmask() · Bob Liu · 2012-02-16
[PATCH 07/40] C6X: Use set_current_blocked() and block_sigmask() · Matt Fleming · 2012-02-14
[PATCH 09/40] frv: Use set_current_blocked() and block_sigmask() · Matt Fleming · 2012-02-14
[PATCH 10/40] h8300: Use set_current_blocked() and block_sigmask() · Matt Fleming · 2012-02-14
[PATCH 13/40] m32r: Use set_current_blocked() and block_sigmask() · Matt Fleming · 2012-02-14
[PATCH 14/40] m68k: Use set_current_blocked() and block_sigmask() · Matt Fleming · 2012-02-14
[PATCH 15/40] microblaze: Don't reimplement force_sigsegv() · Matt Fleming · 2012-02-14
[PATCH 17/40] microblaze: Fix signal masking · Matt Fleming · 2012-02-14
[PATCH 19/40] MIPS: Use set_current_blocked() and block_sigmask() · Matt Fleming · 2012-02-14
[PATCH 20/40] mn10300: Use set_current_blocked() and block_sigmask() · Matt Fleming · 2012-02-14
Re: [PATCH 20/40] mn10300: Use set_current_blocked() and block_sigmask() · David Howells · 2012-02-14
Re: [PATCH 20/40] mn10300: Use set_current_blocked() and block_sigmask() · Oleg Nesterov · 2012-02-14
Re: [PATCH 20/40] mn10300: Use set_current_blocked() and block_sigmask() · David Howells · 2012-02-14
Re: [PATCH 20/40] mn10300: Use set_current_blocked() and block_sigmask() · Oleg Nesterov · 2012-02-14
Re: [PATCH 20/40] mn10300: Use set_current_blocked() and block_sigmask() · Matt Fleming · 2012-02-14
Re: [PATCH 20/40] mn10300: Use set_current_blocked() and block_sigmask() · David Howells · 2012-02-14
Re: [PATCH 20/40] mn10300: Use set_current_blocked() and block_sigmask() · Matt Fleming · 2012-02-15
[PATCH 21/40] OpenRISC: Don't reimplement force_sigsegv() · Matt Fleming · 2012-02-14
Re: [PATCH 21/40] OpenRISC: Don't reimplement force_sigsegv() · Jonas Bonn · 2012-02-15
Re: [PATCH 21/40] OpenRISC: Don't reimplement force_sigsegv() · Matt Fleming · 2012-02-15
Re: [PATCH 21/40] OpenRISC: Don't reimplement force_sigsegv() · Jonas Bonn · 2012-02-15
[PATCH 22/40] OpenRISC: No need to reset handler if SA_ONESHOT · Matt Fleming · 2012-02-14
[PATCH 26/40] powerpc: Use set_current_blocked() and block_sigmask() · Matt Fleming · 2012-02-14
[PATCH 25/40] parisc: Use set_current_blocked() and block_sigmask() · Matt Fleming · 2012-02-14
Re: [PATCH 25/40] parisc: Use set_current_blocked() and block_sigmask() · Kyle McMartin · 2012-04-06
[PATCH 28/40] score: Don't mask signals if we fail to setup signal stack · Matt Fleming · 2012-02-14
[PATCH 29/40] score: Use set_current_blocked() and block_sigmask() · Matt Fleming · 2012-02-14
[PATCH 32/40] sparc: Use block_sigmask() · Matt Fleming · 2012-02-14
Re: [PATCH 32/40] sparc: Use block_sigmask() · David Miller · 2012-02-15
[PATCH 37/40] xtensa: Don't reimplement force_sigsegv() · Matt Fleming · 2012-02-14
[PATCH 36/40] unicore32: Use block_sigmask() · Matt Fleming · 2012-02-14
[PATCH 40/40] xtensa: Use set_current_blocked() and block_sigmask() · Matt Fleming · 2012-02-14
[PATCH 39/40] xtensa: Don't mask signals if we fail to setup signal stack · Matt Fleming · 2012-02-14
[PATCH 38/40] xtensa: No need to reset handler if SA_ONESHOT · Matt Fleming · 2012-02-14
[PATCH 35/40] um: Use set_current_blocked() and block_sigmask() · Matt Fleming · 2012-02-14
[PATCH 34/40] um: Don't restore current->blocked on error · Matt Fleming · 2012-02-14
[PATCH 33/40] tile: Use set_current_blocked() and block_sigmask() · Matt Fleming · 2012-02-14
[PATCH 31/40] sh: Use set_current_blocked() and block_sigmask() · Matt Fleming · 2012-02-14
[PATCH 30/40] sh: No need to reset handler if SA_ONESHOT · Matt Fleming · 2012-02-14
[PATCH 27/40] [S390] Use block_sigmask() · Matt Fleming · 2012-02-14
[PATCH 24/40] OpenRISC: Use set_current_blocked() and block_sigmask() · Matt Fleming · 2012-02-14
[PATCH 23/40] OpenRISC: Don't mask signals if we fail to setup signal stack · Matt Fleming · 2012-02-14
[PATCH 18/40] microblaze: Use set_current_blocked() and block_sigmask() · Matt Fleming · 2012-02-14
[PATCH 16/40] microblaze: No need to reset handler if SA_ONESHOT · Matt Fleming · 2012-02-14
[PATCH 12/40] ia64: Use set_current_blocked() and block_sigmask() · Matt Fleming · 2012-02-14
[PATCH 11/40] Hexagon: Use set_current_blocked() and block_sigmask() · Matt Fleming · 2012-02-14
[PATCH 08/40] cris: Use set_current_blocked() and block_sigmask() · Matt Fleming · 2012-02-14
Re: [PATCH 08/40] cris: Use set_current_blocked() and block_sigmask() · Jesper Nilsson · 2012-02-15
Mark Salter · 2012-02-14
Matt Fleming · 2012-02-14
Mark Salter · 2012-02-14
Matt Fleming · 2012-02-14
Oleg Nesterov · 2012-02-14
Matt Fleming · 2012-02-15
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