The patch titled kernel/irq_work.c: use llist in irq_work has been removed from the -mm tree. Its filename was kernel-irq_workc-use-llist-in-irq_work.patch This patch was dropped because an updated version will be merged The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: kernel/irq_work.c: use llist in irq_work From: Huang Ying <ying.huang@xxxxxxxxx> Use llist in irq_work instead of the lock-less linked list implementation in irq_work to avoid the code duplication. Signed-off-by: Huang Ying <ying.huang@xxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Andi Kleen <andi@xxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/irq_work.h | 15 +++--- kernel/irq_work.c | 92 ++++++++++++------------------------- 2 files changed, 41 insertions(+), 66 deletions(-) diff -puN include/linux/irq_work.h~kernel-irq_workc-use-llist-in-irq_work include/linux/irq_work.h --- a/include/linux/irq_work.h~kernel-irq_workc-use-llist-in-irq_work +++ a/include/linux/irq_work.h @@ -1,20 +1,23 @@ #ifndef _LINUX_IRQ_WORK_H #define _LINUX_IRQ_WORK_H +#include <linux/llist.h> + struct irq_work { - struct irq_work *next; + unsigned long flags; + struct llist_node llnode; void (*func)(struct irq_work *); }; static inline -void init_irq_work(struct irq_work *entry, void (*func)(struct irq_work *)) +void init_irq_work(struct irq_work *work, void (*func)(struct irq_work *)) { - entry->next = NULL; - entry->func = func; + work->flags = 0; + work->func = func; } -bool irq_work_queue(struct irq_work *entry); +bool irq_work_queue(struct irq_work *work); void irq_work_run(void); -void irq_work_sync(struct irq_work *entry); +void irq_work_sync(struct irq_work *work); #endif /* _LINUX_IRQ_WORK_H */ diff -puN kernel/irq_work.c~kernel-irq_workc-use-llist-in-irq_work kernel/irq_work.c --- a/kernel/irq_work.c~kernel-irq_workc-use-llist-in-irq_work +++ a/kernel/irq_work.c @@ -10,7 +10,6 @@ #include <linux/irq_work.h> #include <linux/percpu.h> #include <linux/hardirq.h> -#include <asm/processor.h> /* * An entry can be in one of four states: @@ -19,54 +18,34 @@ * claimed NULL, 3 -> {pending} : claimed to be enqueued * pending next, 3 -> {busy} : queued, pending callback * busy NULL, 2 -> {free, claimed} : callback in progress, can be claimed - * - * We use the lower two bits of the next pointer to keep PENDING and BUSY - * flags. */ #define IRQ_WORK_PENDING 1UL #define IRQ_WORK_BUSY 2UL #define IRQ_WORK_FLAGS 3UL -static inline bool irq_work_is_set(struct irq_work *entry, int flags) -{ - return (unsigned long)entry->next & flags; -} - -static inline struct irq_work *irq_work_next(struct irq_work *entry) -{ - unsigned long next = (unsigned long)entry->next; - next &= ~IRQ_WORK_FLAGS; - return (struct irq_work *)next; -} - -static inline struct irq_work *next_flags(struct irq_work *entry, int flags) -{ - unsigned long next = (unsigned long)entry; - next |= flags; - return (struct irq_work *)next; -} - -static DEFINE_PER_CPU(struct irq_work *, irq_work_list); +static DEFINE_PER_CPU(struct llist_head, irq_work_list); /* * Claim the entry so that no one else will poke at it. */ -static bool irq_work_claim(struct irq_work *entry) +static bool irq_work_claim(struct irq_work *work) { - struct irq_work *next, *nflags; + unsigned long flags, nflags; - do { - next = entry->next; - if ((unsigned long)next & IRQ_WORK_PENDING) + for (;;) { + flags = work->flags; + if (flags & IRQ_WORK_PENDING) return false; - nflags = next_flags(next, IRQ_WORK_FLAGS); - } while (cmpxchg(&entry->next, next, nflags) != next); + nflags = flags | IRQ_WORK_FLAGS; + if (cmpxchg(&work->flags, flags, nflags) == flags) + break; + cpu_relax(); + } return true; } - void __weak arch_irq_work_raise(void) { /* @@ -77,20 +56,13 @@ void __weak arch_irq_work_raise(void) /* * Queue the entry and raise the IPI if needed. */ -static void __irq_work_queue(struct irq_work *entry) +static void __irq_work_queue(struct irq_work *work) { - struct irq_work *next; - preempt_disable(); - do { - next = __this_cpu_read(irq_work_list); - /* Can assign non-atomic because we keep the flags set. */ - entry->next = next_flags(next, IRQ_WORK_FLAGS); - } while (this_cpu_cmpxchg(irq_work_list, next, entry) != next); - + llist_add(&work->llnode, &__get_cpu_var(irq_work_list)); /* The list was empty, raise self-interrupt to start processing. */ - if (!irq_work_next(entry)) + if (!work->llnode.next) arch_irq_work_raise(); preempt_enable(); @@ -102,16 +74,16 @@ static void __irq_work_queue(struct irq_ * * Can be re-enqueued while the callback is still in progress. */ -bool irq_work_queue(struct irq_work *entry) +bool irq_work_queue(struct irq_work *work) { - if (!irq_work_claim(entry)) { + if (!irq_work_claim(work)) { /* * Already enqueued, can't do! */ return false; } - __irq_work_queue(entry); + __irq_work_queue(work); return true; } EXPORT_SYMBOL_GPL(irq_work_queue); @@ -122,34 +94,34 @@ EXPORT_SYMBOL_GPL(irq_work_queue); */ void irq_work_run(void) { - struct irq_work *list; + struct irq_work *work; + struct llist_head *this_list; + struct llist_node *llnode; - if (this_cpu_read(irq_work_list) == NULL) + this_list = &__get_cpu_var(irq_work_list); + if (llist_empty(this_list)) return; BUG_ON(!in_irq()); BUG_ON(!irqs_disabled()); - list = this_cpu_xchg(irq_work_list, NULL); - - while (list != NULL) { - struct irq_work *entry = list; + llnode = llist_del_all(this_list); + while (llnode != NULL) { + work = llist_entry(llnode, struct irq_work, llnode); - list = irq_work_next(list); + llnode = llnode->next; /* - * Clear the PENDING bit, after this point the @entry + * Clear the PENDING bit, after this point the @work * can be re-used. */ - entry->next = next_flags(NULL, IRQ_WORK_BUSY); - entry->func(entry); + work->flags = IRQ_WORK_BUSY; + work->func(work); /* * Clear the BUSY bit and return to the free state if * no-one else claimed it meanwhile. */ - (void)cmpxchg(&entry->next, - next_flags(NULL, IRQ_WORK_BUSY), - NULL); + (void)cmpxchg(&work->flags, IRQ_WORK_BUSY, 0); } } EXPORT_SYMBOL_GPL(irq_work_run); @@ -158,11 +130,11 @@ EXPORT_SYMBOL_GPL(irq_work_run); * Synchronize against the irq_work @entry, ensures the entry is not * currently in use. */ -void irq_work_sync(struct irq_work *entry) +void irq_work_sync(struct irq_work *work) { WARN_ON_ONCE(irqs_disabled()); - while (irq_work_is_set(entry, IRQ_WORK_BUSY)) + while (work->flags & IRQ_WORK_BUSY) cpu_relax(); } EXPORT_SYMBOL_GPL(irq_work_sync); _ Patches currently in -mm which might be from ying.huang@xxxxxxxxx are llist-make-all-llist-functions-inline.patch llist-define-macro-to-check-nmi-safe-cmpxchg.patch llist-move-cpu_relax-after-cmpxchg.patch net-rds-replace-xlist-in-net-rds-xlisth-with-llist.patch lib-bitmapc-quiet-sparse-noise-about-address-space.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html