forked from luck/tmp_suning_uos_patched
workqueue: introduce WORK_OFFQ_FLAG_*
Low WORK_STRUCT_FLAG_BITS bits of work_struct->data contain WORK_STRUCT_FLAG_* and flush color. If the work item is queued, the rest point to the cpu_workqueue with WORK_STRUCT_CWQ set; otherwise, WORK_STRUCT_CWQ is clear and the bits contain the last CPU number - either a real CPU number or one of WORK_CPU_*. Scheduled addition of mod_delayed_work[_on]() requires an additional flag, which is used only while a work item is off queue. There are more than enough bits to represent off-queue CPU number on both 32 and 64bits. This patch introduces WORK_OFFQ_FLAG_* which occupy the lower part of the @work->data high bits while off queue. This patch doesn't define any actual OFFQ flag yet. Off-queue CPU number is now shifted by WORK_OFFQ_CPU_SHIFT, which adds the number of bits used by OFFQ flags to WORK_STRUCT_FLAG_SHIFT, to make room for OFFQ flags. To avoid shift width warning with large WORK_OFFQ_FLAG_BITS, ulong cast is added to WORK_STRUCT_NO_CPU and, just in case, BUILD_BUG_ON() to check that there are enough bits to accomodate off-queue CPU number is added. This patch doesn't make any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org>
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@ -68,9 +68,15 @@ enum {
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WORK_STRUCT_FLAG_BITS = WORK_STRUCT_COLOR_SHIFT +
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WORK_STRUCT_COLOR_BITS,
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/* data contains off-queue information when !WORK_STRUCT_CWQ */
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WORK_OFFQ_FLAG_BASE = WORK_STRUCT_FLAG_BITS,
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WORK_OFFQ_FLAG_BITS = 0,
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WORK_OFFQ_CPU_SHIFT = WORK_OFFQ_FLAG_BASE + WORK_OFFQ_FLAG_BITS,
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/* convenience constants */
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WORK_STRUCT_FLAG_MASK = (1UL << WORK_STRUCT_FLAG_BITS) - 1,
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WORK_STRUCT_WQ_DATA_MASK = ~WORK_STRUCT_FLAG_MASK,
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WORK_STRUCT_NO_CPU = WORK_CPU_NONE << WORK_STRUCT_FLAG_BITS,
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WORK_STRUCT_NO_CPU = (unsigned long)WORK_CPU_NONE << WORK_OFFQ_CPU_SHIFT,
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/* bit mask for work_busy() return values */
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WORK_BUSY_PENDING = 1 << 0,
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@ -533,9 +533,9 @@ static int work_next_color(int color)
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}
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/*
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* A work's data points to the cwq with WORK_STRUCT_CWQ set while the
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* work is on queue. Once execution starts, WORK_STRUCT_CWQ is
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* cleared and the work data contains the cpu number it was last on.
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* While queued, %WORK_STRUCT_CWQ is set and non flag bits of a work's data
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* contain the pointer to the queued cwq. Once execution starts, the flag
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* is cleared and the high bits contain OFFQ flags and CPU number.
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*
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* set_work_cwq(), set_work_cpu_and_clear_pending() and clear_work_data()
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* can be used to set the cwq, cpu or clear work->data. These functions
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@ -565,7 +565,7 @@ static void set_work_cwq(struct work_struct *work,
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static void set_work_cpu_and_clear_pending(struct work_struct *work,
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unsigned int cpu)
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{
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set_work_data(work, cpu << WORK_STRUCT_FLAG_BITS, 0);
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set_work_data(work, (unsigned long)cpu << WORK_OFFQ_CPU_SHIFT, 0);
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}
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static void clear_work_data(struct work_struct *work)
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@ -592,7 +592,7 @@ static struct global_cwq *get_work_gcwq(struct work_struct *work)
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return ((struct cpu_workqueue_struct *)
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(data & WORK_STRUCT_WQ_DATA_MASK))->pool->gcwq;
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cpu = data >> WORK_STRUCT_FLAG_BITS;
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cpu = data >> WORK_OFFQ_CPU_SHIFT;
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if (cpu == WORK_CPU_NONE)
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return NULL;
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@ -3724,6 +3724,10 @@ static int __init init_workqueues(void)
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unsigned int cpu;
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int i;
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/* make sure we have enough bits for OFFQ CPU number */
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BUILD_BUG_ON((1LU << (BITS_PER_LONG - WORK_OFFQ_CPU_SHIFT)) <
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WORK_CPU_LAST);
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cpu_notifier(workqueue_cpu_up_callback, CPU_PRI_WORKQUEUE_UP);
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cpu_notifier(workqueue_cpu_down_callback, CPU_PRI_WORKQUEUE_DOWN);
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