From e120153ddf8620fd0a194d301e9c5a8b28483bb5 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 22 Jul 2010 14:14:25 +0200 Subject: workqueue: fix how cpu number is stored in work->data Once a work starts execution, its data contains the cpu number it was on instead of pointing to cwq. This is added by commit 7a22ad75 (workqueue: carry cpu number in work data once execution starts) to reliably determine the work was last on even if the workqueue itself was destroyed inbetween. Whether data points to a cwq or contains a cpu number was distinguished by comparing the value against PAGE_OFFSET. The assumption was that a cpu number should be below PAGE_OFFSET while a pointer to cwq should be above it. However, on architectures which use separate address spaces for user and kernel spaces, this doesn't hold as PAGE_OFFSET is zero. Fix it by using an explicit flag, WORK_STRUCT_CWQ, to mark what the data field contains. If the flag is set, it's pointing to a cwq; otherwise, it contains a cpu number. Reported on s390 and microblaze during linux-next testing. Signed-off-by: Tejun Heo Reported-by: Sachin Sant Reported-by: Michal Simek Reported-by: Martin Schwidefsky Tested-by: Martin Schwidefsky Tested-by: Michal Simek --- include/linux/workqueue.h | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) (limited to 'include/linux/workqueue.h') diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index d74a529ed13e..5f76001c4e6d 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -25,17 +25,19 @@ typedef void (*work_func_t)(struct work_struct *work); enum { WORK_STRUCT_PENDING_BIT = 0, /* work item is pending execution */ - WORK_STRUCT_LINKED_BIT = 1, /* next work is linked to this one */ + WORK_STRUCT_CWQ_BIT = 1, /* data points to cwq */ + WORK_STRUCT_LINKED_BIT = 2, /* next work is linked to this one */ #ifdef CONFIG_DEBUG_OBJECTS_WORK - WORK_STRUCT_STATIC_BIT = 2, /* static initializer (debugobjects) */ - WORK_STRUCT_COLOR_SHIFT = 3, /* color for workqueue flushing */ + WORK_STRUCT_STATIC_BIT = 3, /* static initializer (debugobjects) */ + WORK_STRUCT_COLOR_SHIFT = 4, /* color for workqueue flushing */ #else - WORK_STRUCT_COLOR_SHIFT = 2, /* color for workqueue flushing */ + WORK_STRUCT_COLOR_SHIFT = 3, /* color for workqueue flushing */ #endif WORK_STRUCT_COLOR_BITS = 4, WORK_STRUCT_PENDING = 1 << WORK_STRUCT_PENDING_BIT, + WORK_STRUCT_CWQ = 1 << WORK_STRUCT_CWQ_BIT, WORK_STRUCT_LINKED = 1 << WORK_STRUCT_LINKED_BIT, #ifdef CONFIG_DEBUG_OBJECTS_WORK WORK_STRUCT_STATIC = 1 << WORK_STRUCT_STATIC_BIT, @@ -56,8 +58,8 @@ enum { WORK_CPU_LAST = WORK_CPU_NONE, /* - * Reserve 6 bits off of cwq pointer w/ debugobjects turned - * off. This makes cwqs aligned to 64 bytes which isn't too + * Reserve 7 bits off of cwq pointer w/ debugobjects turned + * off. This makes cwqs aligned to 128 bytes which isn't too * excessive while allowing 15 workqueue flush colors. */ WORK_STRUCT_FLAG_BITS = WORK_STRUCT_COLOR_SHIFT + -- cgit v1.2.3