Messages in this thread Patch in this message | | | Date | Sun, 20 Jun 2004 11:42:24 +0530 | From | Dipankar Sarma <> | Subject | Re: [PATCH] reduce rcu_head size [2/2] |
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On Sat, Jun 19, 2004 at 12:04:14PM -0700, Andrew Morton wrote: > Dipankar Sarma <dipankar@in.ibm.com> wrote: > > > > This patch changes the call_rcu() API and avoids passing an > > argument to the callback function as suggested by Rusty. > > This breaks the bridge driver: > > > static void destroy_nbp(struct rcu_head *head) > > int br_add_if(struct net_bridge *br, struct net_device *dev) > { > struct net_bridge_port *p; > > ... > destroy_nbp(p);
Crap. New patch that compiles fine.
This patch changes the call_rcu() API and avoids passing an argument to the callback function as suggested by Rusty. Instead, it is assumed that the user has embedded the rcu head into a structure that is useful in the callback and the rcu_head pointer is passed to the callback. The callback can use container_of() to get the pointer to its structure and work with it. Together with the rcu-singly-link patch, it reduces the rcu_head size by 50%. Considering that we use these in things like struct dentry and struct dst_entry, this is good savings in space.
An example :
struct my_struct { struct rcu_head rcu; int x; int y; };
void my_rcu_callback(struct rcu_head *head) { struct my_struct *p = container_of(head, struct my_struct, rcu); free(p); }
void my_delete(struct my_struct *p) { ... call_rcu(&p->rcu, my_rcu_callback); ... }
Signed-Off-By: Dipankar Sarma <dipankar@in.ibm.com>
arch/ppc64/mm/tlb.c | 7 ++++--- fs/dcache.c | 6 +++--- include/linux/rcupdate.h | 10 ++++------ include/net/dst.h | 6 ++++++ ipc/util.c | 25 ++++++++++++++++++++----- kernel/auditsc.c | 7 ++++--- kernel/rcupdate.c | 25 +++++++++++++++---------- net/bridge/br_if.c | 13 +++++++++---- net/decnet/dn_route.c | 4 ++-- net/ipv4/route.c | 4 ++-- security/selinux/netif.c | 6 +++--- 11 files changed, 72 insertions(+), 41 deletions(-)
diff -puN fs/dcache.c~rcu-no-arg fs/dcache.c --- linux-2.6.6-rcu/fs/dcache.c~rcu-no-arg 2004-06-12 00:17:28.000000000 +0530 +++ linux-2.6.6-rcu-dipankar/fs/dcache.c 2004-06-12 00:17:28.000000000 +0530 @@ -61,9 +61,9 @@ struct dentry_stat_t dentry_stat = { .age_limit = 45, }; -static void d_callback(void *arg) +static void d_callback(struct rcu_head *head) { - struct dentry * dentry = (struct dentry *)arg; + struct dentry * dentry = container_of(head, struct dentry, d_rcu); if (dname_external(dentry)) { kfree(dentry->d_qstr); @@ -79,7 +79,7 @@ static void d_free(struct dentry *dentry { if (dentry->d_op && dentry->d_op->d_release) dentry->d_op->d_release(dentry); - call_rcu(&dentry->d_rcu, d_callback, dentry); + call_rcu(&dentry->d_rcu, d_callback); } /* diff -puN include/linux/rcupdate.h~rcu-no-arg include/linux/rcupdate.h --- linux-2.6.6-rcu/include/linux/rcupdate.h~rcu-no-arg 2004-06-12 00:17:28.000000000 +0530 +++ linux-2.6.6-rcu-dipankar/include/linux/rcupdate.h 2004-06-12 00:17:28.000000000 +0530 @@ -45,18 +45,16 @@ * struct rcu_head - callback structure for use with RCU * @next: next update requests in a list * @func: actual update function to call after the grace period. - * @arg: argument to be passed to the actual update function. */ struct rcu_head { struct rcu_head *next; - void (*func)(void *obj); - void *arg; + void (*func)(struct rcu_head *head); }; -#define RCU_HEAD_INIT(head) { .next = NULL, .func = NULL, .arg = NULL } +#define RCU_HEAD_INIT(head) { .next = NULL, .func = NULL } #define RCU_HEAD(head) struct rcu_head head = RCU_HEAD_INIT(head) #define INIT_RCU_HEAD(ptr) do { \ - (ptr)->next = NULL; (ptr)->func = NULL; (ptr)->arg = NULL; \ + (ptr)->next = NULL; (ptr)->func = NULL; \ } while (0) @@ -128,7 +126,7 @@ extern void rcu_check_callbacks(int cpu, /* Exported interfaces */ extern void FASTCALL(call_rcu(struct rcu_head *head, - void (*func)(void *arg), void *arg)); + void (*func)(struct rcu_head *head))); extern void synchronize_kernel(void); #endif /* __KERNEL__ */ diff -puN include/net/dst.h~rcu-no-arg include/net/dst.h --- linux-2.6.6-rcu/include/net/dst.h~rcu-no-arg 2004-06-12 00:17:28.000000000 +0530 +++ linux-2.6.6-rcu-dipankar/include/net/dst.h 2004-06-12 00:17:29.000000000 +0530 @@ -182,6 +182,12 @@ static inline void dst_free(struct dst_e __dst_free(dst); } +static inline void dst_rcu_free(struct rcu_head *head) +{ + struct dst_entry *dst = container_of(head, struct dst_entry, rcu_head); + dst_free(dst); +} + static inline void dst_confirm(struct dst_entry *dst) { if (dst) diff -puN ipc/util.c~rcu-no-arg ipc/util.c --- linux-2.6.6-rcu/ipc/util.c~rcu-no-arg 2004-06-12 00:17:28.000000000 +0530 +++ linux-2.6.6-rcu-dipankar/ipc/util.c 2004-06-12 00:17:28.000000000 +0530 @@ -331,25 +331,40 @@ void* ipc_rcu_alloc(int size) * Since RCU callback function is called in bh, * we need to defer the vfree to schedule_work */ -static void ipc_schedule_free(void* arg) +static void ipc_schedule_free(struct rcu_head *head) { - struct ipc_rcu_vmalloc *free = arg; + struct ipc_rcu_vmalloc *free = + container_of(head, struct ipc_rcu_vmalloc, rcu); INIT_WORK(&free->work, vfree, free); schedule_work(&free->work); } +/** + * ipc_immediate_free - free ipc + rcu space + * + * Free from the RCU callback context + * + */ +static void ipc_immediate_free(struct rcu_head *head) +{ + struct ipc_rcu_kmalloc *free = + container_of(head, struct ipc_rcu_kmalloc, rcu); + kfree(free); +} + + + void ipc_rcu_free(void* ptr, int size) { if (rcu_use_vmalloc(size)) { struct ipc_rcu_vmalloc *free; free = ptr - sizeof(*free); - call_rcu(&free->rcu, ipc_schedule_free, free); + call_rcu(&free->rcu, ipc_schedule_free); } else { struct ipc_rcu_kmalloc *free; free = ptr - sizeof(*free); - /* kfree takes a "const void *" so gcc warns. So we cast. */ - call_rcu(&free->rcu, (void (*)(void *))kfree, free); + call_rcu(&free->rcu, ipc_immediate_free); } } diff -puN kernel/rcupdate.c~rcu-no-arg kernel/rcupdate.c --- linux-2.6.6-rcu/kernel/rcupdate.c~rcu-no-arg 2004-06-12 00:17:28.000000000 +0530 +++ linux-2.6.6-rcu-dipankar/kernel/rcupdate.c 2004-06-12 00:20:36.000000000 +0530 @@ -59,20 +59,18 @@ static DEFINE_PER_CPU(struct tasklet_str * call_rcu - Queue an RCU update request. * @head: structure to be used for queueing the RCU updates. * @func: actual update function to be invoked after the grace period - * @arg: argument to be passed to the update function * * The update function will be invoked as soon as all CPUs have performed * a context switch or been seen in the idle loop or in a user process. * The read-side of critical section that use call_rcu() for updation must * be protected by rcu_read_lock()/rcu_read_unlock(). */ -void fastcall call_rcu(struct rcu_head *head, void (*func)(void *arg), void *arg) +void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu)) { int cpu; unsigned long flags; head->func = func; - head->arg = arg; head->next = NULL; local_irq_save(flags); cpu = smp_processor_id(); @@ -91,7 +89,7 @@ static void rcu_do_batch(struct rcu_head while (list) { next = list->next; - list->func(list->arg); + list->func(list); list = next; } } @@ -302,11 +300,18 @@ void __init rcu_init(void) register_cpu_notifier(&rcu_nb); } +struct rcu_synchronize { + struct rcu_head head; + struct completion completion; +}; /* Because of FASTCALL declaration of complete, we use this wrapper */ -static void wakeme_after_rcu(void *completion) +static void wakeme_after_rcu(struct rcu_head *head) { - complete(completion); + struct rcu_synchronize *rcu; + + rcu = container_of(head, struct rcu_synchronize, head); + complete(&rcu->completion); } /** @@ -315,14 +320,14 @@ static void wakeme_after_rcu(void *compl */ void synchronize_kernel(void) { - struct rcu_head rcu; - DECLARE_COMPLETION(completion); + struct rcu_synchronize rcu; + init_completion(&rcu.completion); /* Will wake me after RCU finished */ - call_rcu(&rcu, wakeme_after_rcu, &completion); + call_rcu(&rcu.head, wakeme_after_rcu); /* Wait for it */ - wait_for_completion(&completion); + wait_for_completion(&rcu.completion); } diff -puN net/bridge/br_if.c~rcu-no-arg net/bridge/br_if.c --- linux-2.6.6-rcu/net/bridge/br_if.c~rcu-no-arg 2004-06-12 00:17:28.000000000 +0530 +++ linux-2.6.6-rcu-dipankar/net/bridge/br_if.c 2004-06-20 11:35:12.000000000 +0530 @@ -75,10 +75,8 @@ static int br_initial_port_cost(struct n return 100; /* assume old 10Mbps */ } -static void destroy_nbp(void *arg) +static void destroy_nbp(struct net_bridge_port *p) { - struct net_bridge_port *p = arg; - p->dev->br_port = NULL; BUG_ON(timer_pending(&p->message_age_timer)); @@ -89,6 +87,13 @@ static void destroy_nbp(void *arg) kfree(p); } +static void destroy_nbp_rcu(struct rcu_head *head) +{ + struct net_bridge_port *p = + container_of(head, struct net_bridge_port, rcu); + destroy_nbp(p); +} + /* called under bridge lock */ static void del_nbp(struct net_bridge_port *p) { @@ -106,7 +111,7 @@ static void del_nbp(struct net_bridge_po del_timer(&p->forward_delay_timer); del_timer(&p->hold_timer); - call_rcu(&p->rcu, destroy_nbp, p); + call_rcu(&p->rcu, destroy_nbp_rcu); } static void del_br(struct net_bridge *br) diff -puN net/decnet/dn_route.c~rcu-no-arg net/decnet/dn_route.c --- linux-2.6.6-rcu/net/decnet/dn_route.c~rcu-no-arg 2004-06-12 00:17:28.000000000 +0530 +++ linux-2.6.6-rcu-dipankar/net/decnet/dn_route.c 2004-06-12 00:17:29.000000000 +0530 @@ -146,14 +146,14 @@ static __inline__ unsigned dn_hash(unsig static inline void dnrt_free(struct dn_route *rt) { - call_rcu(&rt->u.dst.rcu_head, (void (*)(void *))dst_free, &rt->u.dst); + call_rcu(&rt->u.dst.rcu_head, dst_rcu_free); } static inline void dnrt_drop(struct dn_route *rt) { if (rt) dst_release(&rt->u.dst); - call_rcu(&rt->u.dst.rcu_head, (void (*)(void *))dst_free, &rt->u.dst); + call_rcu(&rt->u.dst.rcu_head, dst_rcu_free); } static void dn_dst_check_expire(unsigned long dummy) diff -puN net/ipv4/route.c~rcu-no-arg net/ipv4/route.c --- linux-2.6.6-rcu/net/ipv4/route.c~rcu-no-arg 2004-06-12 00:17:28.000000000 +0530 +++ linux-2.6.6-rcu-dipankar/net/ipv4/route.c 2004-06-12 00:17:29.000000000 +0530 @@ -437,13 +437,13 @@ static struct file_operations rt_cpu_seq static __inline__ void rt_free(struct rtable *rt) { - call_rcu(&rt->u.dst.rcu_head, (void (*)(void *))dst_free, &rt->u.dst); + call_rcu(&rt->u.dst.rcu_head, dst_rcu_free); } static __inline__ void rt_drop(struct rtable *rt) { ip_rt_put(rt); - call_rcu(&rt->u.dst.rcu_head, (void (*)(void *))dst_free, &rt->u.dst); + call_rcu(&rt->u.dst.rcu_head, dst_rcu_free); } static __inline__ int rt_fast_clean(struct rtable *rth) diff -puN arch/ppc64/mm/tlb.c~rcu-no-arg arch/ppc64/mm/tlb.c --- linux-2.6.6-rcu/arch/ppc64/mm/tlb.c~rcu-no-arg 2004-06-12 00:23:38.000000000 +0530 +++ linux-2.6.6-rcu-dipankar/arch/ppc64/mm/tlb.c 2004-06-12 00:32:37.000000000 +0530 @@ -127,9 +127,10 @@ void pte_free_now(struct page *ptepage) pte_free(ptepage); } -static void pte_free_rcu_callback(void *arg) +static void pte_free_rcu_callback(struct rcu_head *head) { - struct pte_freelist_batch *batch = arg; + struct pte_freelist_batch *batch = + container_of(head, struct pte_freelist_batch, rcu); unsigned int i; for (i = 0; i < batch->index; i++) @@ -140,7 +141,7 @@ static void pte_free_rcu_callback(void * void pte_free_submit(struct pte_freelist_batch *batch) { INIT_RCU_HEAD(&batch->rcu); - call_rcu(&batch->rcu, pte_free_rcu_callback, batch); + call_rcu(&batch->rcu, pte_free_rcu_callback); } void pte_free_finish(void) diff -puN kernel/auditsc.c~rcu-no-arg kernel/auditsc.c --- linux-2.6.6-rcu/kernel/auditsc.c~rcu-no-arg 2004-06-12 00:35:09.000000000 +0530 +++ linux-2.6.6-rcu-dipankar/kernel/auditsc.c 2004-06-12 00:40:37.000000000 +0530 @@ -177,9 +177,10 @@ static inline int audit_add_rule(struct return 0; } -static void audit_free_rule(void *arg) +static void audit_free_rule(struct rcu_head *head) { - kfree(arg); + struct audit_entry *e = container_of(head, struct audit_entry, rcu); + kfree(e); } /* Note that audit_add_rule and audit_del_rule are called via @@ -195,7 +196,7 @@ static inline int audit_del_rule(struct list_for_each_entry(e, list, list) { if (!audit_compare_rule(rule, &e->rule)) { list_del_rcu(&e->list); - call_rcu(&e->rcu, audit_free_rule, e); + call_rcu(&e->rcu, audit_free_rule); return 0; } } diff -puN security/selinux/netif.c~rcu-no-arg security/selinux/netif.c --- linux-2.6.6-rcu/security/selinux/netif.c~rcu-no-arg 2004-06-12 00:38:57.000000000 +0530 +++ linux-2.6.6-rcu-dipankar/security/selinux/netif.c 2004-06-12 00:40:28.000000000 +0530 @@ -134,9 +134,9 @@ out: return netif; } -static void sel_netif_free(void *p) +static void sel_netif_free(struct rcu_head *p) { - struct sel_netif *netif = p; + struct sel_netif *netif = container_of(p, struct sel_netif, rcu_head); DEBUGP("%s: %s\n", __FUNCTION__, netif->nsec.dev->name); kfree(netif); @@ -151,7 +151,7 @@ static void sel_netif_destroy(struct sel sel_netif_total--; spin_unlock_bh(&sel_netif_lock); - call_rcu(&netif->rcu_head, sel_netif_free, netif); + call_rcu(&netif->rcu_head, sel_netif_free); } void sel_netif_put(struct sel_netif *netif) _ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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