From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 28 Jun 2012 08:45:09 +1000 From: Anton Blanchard To: benh@kernel.crashing.org, paulus@samba.org Subject: [PATCH] powerpc: check_and_cede_processor never cedes Message-ID: <20120628084509.4caec81d@kryten> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Cc: linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Commit f948501b36c6 ("Make hard_irq_disable() actually hard-disable interrupts") caused check_and_cede_processor to stop working. ->irq_happened will never be zero right after a hard_irq_disable so the compiler removes the call to cede_processor completely. The bug was introduced back in the lazy interrupt handling rework of 3.4 but was hidden until recently because hard_irq_disable did nothing. This issue will eventually appear in 3.4 stable since the hard_irq_disable fix is marked stable, so mark this one for stable too. Signed-off-by: Anton Blanchard Cc: stable@vger.kernel.org --- Index: linux-build/arch/powerpc/platforms/pseries/processor_idle.c =================================================================== --- linux-build.orig/arch/powerpc/platforms/pseries/processor_idle.c 2012-06-27 21:20:45.403761715 +1000 +++ linux-build/arch/powerpc/platforms/pseries/processor_idle.c 2012-06-27 21:57:14.796788823 +1000 @@ -106,7 +106,7 @@ static void check_and_cede_processor(voi * we first hard disable then check. */ hard_irq_disable(); - if (get_paca()->irq_happened == 0) + if (get_paca()->irq_happened == PACA_IRQ_HARD_DIS) cede_processor(); }