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-rw-r--r--net/rds/ib_rdma.c214
-rw-r--r--net/rds/xlist.h110
2 files changed, 282 insertions, 42 deletions
diff --git a/net/rds/ib_rdma.c b/net/rds/ib_rdma.c
index 64b5ede037c8..8c40391de5a2 100644
--- a/net/rds/ib_rdma.c
+++ b/net/rds/ib_rdma.c
@@ -36,7 +36,10 @@
#include "rds.h"
#include "ib.h"
+#include "xlist.h"
+static DEFINE_PER_CPU(unsigned long, clean_list_grace);
+#define CLEAN_LIST_BUSY_BIT 0
/*
* This is stored as mr->r_trans_private.
@@ -45,7 +48,11 @@ struct rds_ib_mr {
struct rds_ib_device *device;
struct rds_ib_mr_pool *pool;
struct ib_fmr *fmr;
- struct list_head list;
+
+ struct xlist_head xlist;
+
+ /* unmap_list is for freeing */
+ struct list_head unmap_list;
unsigned int remap_count;
struct scatterlist *sg;
@@ -61,12 +68,14 @@ struct rds_ib_mr_pool {
struct mutex flush_lock; /* serialize fmr invalidate */
struct work_struct flush_worker; /* flush worker */
- spinlock_t list_lock; /* protect variables below */
atomic_t item_count; /* total # of MRs */
atomic_t dirty_count; /* # dirty of MRs */
- struct list_head drop_list; /* MRs that have reached their max_maps limit */
- struct list_head free_list; /* unused MRs */
- struct list_head clean_list; /* unused & unamapped MRs */
+
+ struct xlist_head drop_list; /* MRs that have reached their max_maps limit */
+ struct xlist_head free_list; /* unused MRs */
+ struct xlist_head clean_list; /* global unused & unamapped MRs */
+ wait_queue_head_t flush_wait;
+
atomic_t free_pinned; /* memory pinned by free MRs */
unsigned long max_items;
unsigned long max_items_soft;
@@ -74,7 +83,7 @@ struct rds_ib_mr_pool {
struct ib_fmr_attr fmr_attr;
};
-static int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool, int free_all);
+static int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool, int free_all, struct rds_ib_mr **);
static void rds_ib_teardown_mr(struct rds_ib_mr *ibmr);
static void rds_ib_mr_pool_flush_worker(struct work_struct *work);
@@ -212,11 +221,11 @@ struct rds_ib_mr_pool *rds_ib_create_mr_pool(struct rds_ib_device *rds_ibdev)
if (!pool)
return ERR_PTR(-ENOMEM);
- INIT_LIST_HEAD(&pool->free_list);
- INIT_LIST_HEAD(&pool->drop_list);
- INIT_LIST_HEAD(&pool->clean_list);
+ INIT_XLIST_HEAD(&pool->free_list);
+ INIT_XLIST_HEAD(&pool->drop_list);
+ INIT_XLIST_HEAD(&pool->clean_list);
mutex_init(&pool->flush_lock);
- spin_lock_init(&pool->list_lock);
+ init_waitqueue_head(&pool->flush_wait);
INIT_WORK(&pool->flush_worker, rds_ib_mr_pool_flush_worker);
pool->fmr_attr.max_pages = fmr_message_size;
@@ -246,27 +255,50 @@ void rds_ib_get_mr_info(struct rds_ib_device *rds_ibdev, struct rds_info_rdma_co
void rds_ib_destroy_mr_pool(struct rds_ib_mr_pool *pool)
{
cancel_work_sync(&pool->flush_worker);
- rds_ib_flush_mr_pool(pool, 1);
+ rds_ib_flush_mr_pool(pool, 1, NULL);
WARN_ON(atomic_read(&pool->item_count));
WARN_ON(atomic_read(&pool->free_pinned));
kfree(pool);
}
+static void refill_local(struct rds_ib_mr_pool *pool, struct xlist_head *xl,
+ struct rds_ib_mr **ibmr_ret)
+{
+ struct xlist_head *ibmr_xl;
+ ibmr_xl = xlist_del_head_fast(xl);
+ *ibmr_ret = list_entry(ibmr_xl, struct rds_ib_mr, xlist);
+}
+
static inline struct rds_ib_mr *rds_ib_reuse_fmr(struct rds_ib_mr_pool *pool)
{
struct rds_ib_mr *ibmr = NULL;
- unsigned long flags;
+ struct xlist_head *ret;
+ unsigned long *flag;
- spin_lock_irqsave(&pool->list_lock, flags);
- if (!list_empty(&pool->clean_list)) {
- ibmr = list_entry(pool->clean_list.next, struct rds_ib_mr, list);
- list_del_init(&ibmr->list);
- }
- spin_unlock_irqrestore(&pool->list_lock, flags);
+ preempt_disable();
+ flag = &__get_cpu_var(clean_list_grace);
+ set_bit(CLEAN_LIST_BUSY_BIT, flag);
+ ret = xlist_del_head(&pool->clean_list);
+ if (ret)
+ ibmr = list_entry(ret, struct rds_ib_mr, xlist);
+ clear_bit(CLEAN_LIST_BUSY_BIT, flag);
+ preempt_enable();
return ibmr;
}
+static inline void wait_clean_list_grace(void)
+{
+ int cpu;
+ unsigned long *flag;
+
+ for_each_online_cpu(cpu) {
+ flag = &per_cpu(clean_list_grace, cpu);
+ while (test_bit(CLEAN_LIST_BUSY_BIT, flag))
+ cpu_relax();
+ }
+}
+
static struct rds_ib_mr *rds_ib_alloc_fmr(struct rds_ib_device *rds_ibdev)
{
struct rds_ib_mr_pool *pool = rds_ibdev->mr_pool;
@@ -299,7 +331,9 @@ static struct rds_ib_mr *rds_ib_alloc_fmr(struct rds_ib_device *rds_ibdev)
/* We do have some empty MRs. Flush them out. */
rds_ib_stats_inc(s_ib_rdma_mr_pool_wait);
- rds_ib_flush_mr_pool(pool, 0);
+ rds_ib_flush_mr_pool(pool, 0, &ibmr);
+ if (ibmr)
+ return ibmr;
}
ibmr = kzalloc_node(sizeof(*ibmr), GFP_KERNEL, rdsibdev_to_node(rds_ibdev));
@@ -494,33 +528,109 @@ static inline unsigned int rds_ib_flush_goal(struct rds_ib_mr_pool *pool, int fr
}
/*
+ * given an xlist of mrs, put them all into the list_head for more processing
+ */
+static void xlist_append_to_list(struct xlist_head *xlist, struct list_head *list)
+{
+ struct rds_ib_mr *ibmr;
+ struct xlist_head splice;
+ struct xlist_head *cur;
+ struct xlist_head *next;
+
+ splice.next = NULL;
+ xlist_splice(xlist, &splice);
+ cur = splice.next;
+ while (cur) {
+ next = cur->next;
+ ibmr = list_entry(cur, struct rds_ib_mr, xlist);
+ list_add_tail(&ibmr->unmap_list, list);
+ cur = next;
+ }
+}
+
+/*
+ * this takes a list head of mrs and turns it into an xlist of clusters.
+ * each cluster has an xlist of MR_CLUSTER_SIZE mrs that are ready for
+ * reuse.
+ */
+static void list_append_to_xlist(struct rds_ib_mr_pool *pool,
+ struct list_head *list, struct xlist_head *xlist,
+ struct xlist_head **tail_ret)
+{
+ struct rds_ib_mr *ibmr;
+ struct xlist_head *cur_mr = xlist;
+ struct xlist_head *tail_mr = NULL;
+
+ list_for_each_entry(ibmr, list, unmap_list) {
+ tail_mr = &ibmr->xlist;
+ tail_mr->next = NULL;
+ cur_mr->next = tail_mr;
+ cur_mr = tail_mr;
+ }
+ *tail_ret = tail_mr;
+}
+
+/*
* Flush our pool of MRs.
* At a minimum, all currently unused MRs are unmapped.
* If the number of MRs allocated exceeds the limit, we also try
* to free as many MRs as needed to get back to this limit.
*/
-static int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool, int free_all)
+static int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool,
+ int free_all, struct rds_ib_mr **ibmr_ret)
{
struct rds_ib_mr *ibmr, *next;
+ struct xlist_head clean_xlist;
+ struct xlist_head *clean_tail;
LIST_HEAD(unmap_list);
LIST_HEAD(fmr_list);
unsigned long unpinned = 0;
- unsigned long flags;
unsigned int nfreed = 0, ncleaned = 0, free_goal;
int ret = 0;
rds_ib_stats_inc(s_ib_rdma_mr_pool_flush);
- mutex_lock(&pool->flush_lock);
+ if (ibmr_ret) {
+ DEFINE_WAIT(wait);
+ while(!mutex_trylock(&pool->flush_lock)) {
+ ibmr = rds_ib_reuse_fmr(pool);
+ if (ibmr) {
+ *ibmr_ret = ibmr;
+ finish_wait(&pool->flush_wait, &wait);
+ goto out_nolock;
+ }
+
+ prepare_to_wait(&pool->flush_wait, &wait,
+ TASK_UNINTERRUPTIBLE);
+ if (xlist_empty(&pool->clean_list))
+ schedule();
+
+ ibmr = rds_ib_reuse_fmr(pool);
+ if (ibmr) {
+ *ibmr_ret = ibmr;
+ finish_wait(&pool->flush_wait, &wait);
+ goto out_nolock;
+ }
+ }
+ finish_wait(&pool->flush_wait, &wait);
+ } else
+ mutex_lock(&pool->flush_lock);
+
+ if (ibmr_ret) {
+ ibmr = rds_ib_reuse_fmr(pool);
+ if (ibmr) {
+ *ibmr_ret = ibmr;
+ goto out;
+ }
+ }
- spin_lock_irqsave(&pool->list_lock, flags);
/* Get the list of all MRs to be dropped. Ordering matters -
- * we want to put drop_list ahead of free_list. */
- list_splice_init(&pool->free_list, &unmap_list);
- list_splice_init(&pool->drop_list, &unmap_list);
+ * we want to put drop_list ahead of free_list.
+ */
+ xlist_append_to_list(&pool->drop_list, &unmap_list);
+ xlist_append_to_list(&pool->free_list, &unmap_list);
if (free_all)
- list_splice_init(&pool->clean_list, &unmap_list);
- spin_unlock_irqrestore(&pool->list_lock, flags);
+ xlist_append_to_list(&pool->clean_list, &unmap_list);
free_goal = rds_ib_flush_goal(pool, free_all);
@@ -528,19 +638,20 @@ static int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool, int free_all)
goto out;
/* String all ib_mr's onto one list and hand them to ib_unmap_fmr */
- list_for_each_entry(ibmr, &unmap_list, list)
+ list_for_each_entry(ibmr, &unmap_list, unmap_list)
list_add(&ibmr->fmr->list, &fmr_list);
+
ret = ib_unmap_fmr(&fmr_list);
if (ret)
printk(KERN_WARNING "RDS/IB: ib_unmap_fmr failed (err=%d)\n", ret);
/* Now we can destroy the DMA mapping and unpin any pages */
- list_for_each_entry_safe(ibmr, next, &unmap_list, list) {
+ list_for_each_entry_safe(ibmr, next, &unmap_list, unmap_list) {
unpinned += ibmr->sg_len;
__rds_ib_teardown_mr(ibmr);
if (nfreed < free_goal || ibmr->remap_count >= pool->fmr_attr.max_maps) {
rds_ib_stats_inc(s_ib_rdma_mr_free);
- list_del(&ibmr->list);
+ list_del(&ibmr->unmap_list);
ib_dealloc_fmr(ibmr->fmr);
kfree(ibmr);
nfreed++;
@@ -548,9 +659,27 @@ static int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool, int free_all)
ncleaned++;
}
- spin_lock_irqsave(&pool->list_lock, flags);
- list_splice(&unmap_list, &pool->clean_list);
- spin_unlock_irqrestore(&pool->list_lock, flags);
+ if (!list_empty(&unmap_list)) {
+ /* we have to make sure that none of the things we're about
+ * to put on the clean list would race with other cpus trying
+ * to pull items off. The xlist would explode if we managed to
+ * remove something from the clean list and then add it back again
+ * while another CPU was spinning on that same item in xlist_del_head.
+ *
+ * This is pretty unlikely, but just in case wait for an xlist grace period
+ * here before adding anything back into the clean list.
+ */
+ wait_clean_list_grace();
+
+ list_append_to_xlist(pool, &unmap_list, &clean_xlist, &clean_tail);
+ if (ibmr_ret)
+ refill_local(pool, &clean_xlist, ibmr_ret);
+
+ /* refill_local may have emptied our list */
+ if (!xlist_empty(&clean_xlist))
+ xlist_add(clean_xlist.next, clean_tail, &pool->clean_list);
+
+ }
atomic_sub(unpinned, &pool->free_pinned);
atomic_sub(ncleaned, &pool->dirty_count);
@@ -558,6 +687,9 @@ static int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool, int free_all)
out:
mutex_unlock(&pool->flush_lock);
+ if (waitqueue_active(&pool->flush_wait))
+ wake_up(&pool->flush_wait);
+out_nolock:
return ret;
}
@@ -565,7 +697,7 @@ static void rds_ib_mr_pool_flush_worker(struct work_struct *work)
{
struct rds_ib_mr_pool *pool = container_of(work, struct rds_ib_mr_pool, flush_worker);
- rds_ib_flush_mr_pool(pool, 0);
+ rds_ib_flush_mr_pool(pool, 0, NULL);
}
void rds_ib_free_mr(void *trans_private, int invalidate)
@@ -573,20 +705,17 @@ void rds_ib_free_mr(void *trans_private, int invalidate)
struct rds_ib_mr *ibmr = trans_private;
struct rds_ib_device *rds_ibdev = ibmr->device;
struct rds_ib_mr_pool *pool = rds_ibdev->mr_pool;
- unsigned long flags;
rdsdebug("RDS/IB: free_mr nents %u\n", ibmr->sg_len);
/* Return it to the pool's free list */
- spin_lock_irqsave(&pool->list_lock, flags);
if (ibmr->remap_count >= pool->fmr_attr.max_maps)
- list_add(&ibmr->list, &pool->drop_list);
+ xlist_add(&ibmr->xlist, &ibmr->xlist, &pool->drop_list);
else
- list_add(&ibmr->list, &pool->free_list);
+ xlist_add(&ibmr->xlist, &ibmr->xlist, &pool->free_list);
atomic_add(ibmr->sg_len, &pool->free_pinned);
atomic_inc(&pool->dirty_count);
- spin_unlock_irqrestore(&pool->list_lock, flags);
/* If we've pinned too many pages, request a flush */
if (atomic_read(&pool->free_pinned) >= pool->max_free_pinned ||
@@ -595,7 +724,7 @@ void rds_ib_free_mr(void *trans_private, int invalidate)
if (invalidate) {
if (likely(!in_interrupt())) {
- rds_ib_flush_mr_pool(pool, 0);
+ rds_ib_flush_mr_pool(pool, 0, NULL);
} else {
/* We get here if the user created a MR marked
* as use_once and invalidate at the same time. */
@@ -614,7 +743,7 @@ void rds_ib_flush_mrs(void)
struct rds_ib_mr_pool *pool = rds_ibdev->mr_pool;
if (pool)
- rds_ib_flush_mr_pool(pool, 0);
+ rds_ib_flush_mr_pool(pool, 0, NULL);
}
}
@@ -659,3 +788,4 @@ void *rds_ib_get_mr(struct scatterlist *sg, unsigned long nents,
rds_ib_dev_put(rds_ibdev);
return ibmr;
}
+
diff --git a/net/rds/xlist.h b/net/rds/xlist.h
new file mode 100644
index 000000000000..8c21aca49d50
--- /dev/null
+++ b/net/rds/xlist.h
@@ -0,0 +1,110 @@
+#ifndef _LINUX_XLIST_H
+#define _LINUX_XLIST_H
+
+#include <linux/stddef.h>
+#include <linux/poison.h>
+#include <linux/prefetch.h>
+#include <asm/system.h>
+
+struct xlist_head {
+ struct xlist_head *next;
+};
+
+/*
+ * XLIST_PTR_TAIL can be used to prevent double insertion. See
+ * xlist_protect()
+ */
+#define XLIST_PTR_TAIL ((struct xlist_head *)0x1)
+
+static inline void xlist_add(struct xlist_head *new, struct xlist_head *tail, struct xlist_head *head)
+{
+ struct xlist_head *cur;
+ struct xlist_head *check;
+
+ while (1) {
+ cur = head->next;
+ tail->next = cur;
+ check = cmpxchg(&head->next, cur, new);
+ if (check == cur)
+ break;
+ }
+}
+
+/*
+ * To avoid duplicate insertion by two CPUs of the same xlist item
+ * you can call xlist_protect. It will stuff XLIST_PTR_TAIL
+ * into the entry->next pointer with xchg, and only return 1
+ * if there was a NULL there before.
+ *
+ * if xlist_protect returns zero, someone else is busy working
+ * on this entry. Getting a NULL into the entry in a race
+ * free manner is the caller's job.
+ */
+static inline int xlist_protect(struct xlist_head *entry)
+{
+ struct xlist_head *val;
+
+ val = xchg(&entry->next, XLIST_PTR_TAIL);
+ if (val == NULL)
+ return 1;
+ return 0;
+}
+
+static inline struct xlist_head *xlist_del_head(struct xlist_head *head)
+{
+ struct xlist_head *cur;
+ struct xlist_head *check;
+ struct xlist_head *next;
+
+ while (1) {
+ cur = head->next;
+ if (!cur)
+ goto out;
+
+ if (cur == XLIST_PTR_TAIL) {
+ cur = NULL;
+ goto out;
+ }
+
+ next = cur->next;
+ check = cmpxchg(&head->next, cur, next);
+ if (check == cur)
+ goto out;
+ }
+out:
+ return cur;
+}
+
+static inline struct xlist_head *xlist_del_head_fast(struct xlist_head *head)
+{
+ struct xlist_head *cur;
+
+ cur = head->next;
+ if (!cur || cur == XLIST_PTR_TAIL)
+ return NULL;
+
+ head->next = cur->next;
+ return cur;
+}
+
+static inline void xlist_splice(struct xlist_head *list,
+ struct xlist_head *head)
+{
+ struct xlist_head *cur;
+
+ WARN_ON(head->next);
+ cur = xchg(&list->next, NULL);
+ head->next = cur;
+}
+
+static inline void INIT_XLIST_HEAD(struct xlist_head *list)
+{
+ list->next = NULL;
+}
+
+static inline int xlist_empty(struct xlist_head *head)
+{
+ return head->next == NULL || head->next == XLIST_PTR_TAIL;
+}
+
+#endif
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.