[infiniband:for-next 13/14] drivers/infiniband/hw/qib/qib_keys.c:64:23: sparse: incompatible types i

wfg
2012-07-06T08:02:29Z

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Hi Mike,

There are new sparse warnings show up in

tree: git://git.kernel.org/pub/scm/linux/kernel/git/roland/infiniband.git for-next
head: 04c83d3ce5bbb85f81744b51104522f657fd4ecf
commit: e12deda1747e1cc479ea219c5907fd92d0158566 [13/14] IB/qib: RCU locking for MR validation

All sparse warnings:

+ drivers/infiniband/hw/qib/qib_keys.c:64:23: sparse: incompatible types in comparison expression (different address spaces)
drivers/infiniband/hw/qib/qib_keys.c:168:22: sparse: incompatible types in comparison expression (different address spaces)
drivers/infiniband/hw/qib/qib_keys.c:183:14: sparse: incompatible types in comparison expression (different address spaces)
drivers/infiniband/hw/qib/qib_keys.c:266:22: sparse: incompatible types in comparison expression (different address spaces)
drivers/infiniband/hw/qib/qib_keys.c:282:14: sparse: incompatible types in comparison expression (different address spaces)
drivers/infiniband/hw/qib/qib_verbs.c:2010:9: sparse: incorrect type in assignment (different address spaces)
drivers/infiniband/hw/qib/qib_verbs.c:2010:9: expected struct qib_qp *qp0
drivers/infiniband/hw/qib/qib_verbs.c:2010:9: got void [noderef] <asn:4>*<noident>
drivers/infiniband/hw/qib/qib_verbs.c:2011:9: sparse: incorrect type in assignment (different address spaces)
drivers/infiniband/hw/qib/qib_verbs.c:2011:9: expected struct qib_qp *qp1
drivers/infiniband/hw/qib/qib_verbs.c:2011:9: got void [noderef] <asn:4>*<noident>
drivers/infiniband/hw/qib/qib_verbs.c:2036:17: sparse: incorrect type in assignment (different address spaces)
drivers/infiniband/hw/qib/qib_verbs.c:2036:17: expected struct qib_qp *<noident>
drivers/infiniband/hw/qib/qib_verbs.c:2036:17: got void [noderef] <asn:4>*<noident>
drivers/infiniband/hw/qib/qib_verbs.c:2069:9: sparse: incorrect type in assignment (different address spaces)
drivers/infiniband/hw/qib/qib_verbs.c:2069:9: expected struct qib_mregion *dma_mr
drivers/infiniband/hw/qib/qib_verbs.c:2069:9: got void [noderef] <asn:4>*<noident>
drivers/infiniband/hw/qib/qib_verbs.c:2071:17: sparse: incorrect type in assignment (different address spaces)
drivers/infiniband/hw/qib/qib_verbs.c:2071:17: expected struct qib_mregion *<noident>
drivers/infiniband/hw/qib/qib_verbs.c:2071:17: got void [noderef] <asn:4>*<noident>

vim +64 drivers/infiniband/hw/qib/qib_keys.c
61 if (dma_region) {
62 struct qib_mregion *tmr;
63
> 64 tmr = rcu_dereference(dev->dma_mr);
65 if (!tmr) {
66 qib_get_mr(mr);
67 rcu_assign_pointer(dev->dma_mr, mr);

---
0-DAY kernel build testing backend Open Source Technology Centre
Fengguang Wu <wfg@linux.intel.com> Intel Corporation

[-- Attachment #2: 0001-IB-qib-RCU-locking-for-MR-validation.patch --]
[-- Type: text/x-diff, Size: 12563 bytes --]

From e12deda1747e1cc479ea219c5907fd92d0158566 Mon Sep 17 00:00:00 2001
From: Mike Marciniszyn <mike.marciniszyn@intel.com>
Date: Wed, 27 Jun 2012 18:33:19 -0400
Subject: [PATCH] IB/qib: RCU locking for MR validation

Profiling indicates that MR validation locking is expensive. The MR
table is largely read-only and is a suitable candidate for RCU locking.

The patch uses RCU locking during validation to eliminate one
lock/unlock during that validation.

Reviewed-by: Mike Heinz <michael.william.heinz@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
---
drivers/infiniband/hw/qib/qib_keys.c | 98 +++++++++++++++++----------------
drivers/infiniband/hw/qib/qib_mr.c | 7 +++
drivers/infiniband/hw/qib/qib_verbs.c | 4 +-
drivers/infiniband/hw/qib/qib_verbs.h | 7 ++-
4 files changed, 66 insertions(+), 50 deletions(-)

diff --git a/drivers/infiniband/hw/qib/qib_keys.c b/drivers/infiniband/hw/qib/qib_keys.c
index 8b5ee3a..970165b 100644
--- a/drivers/infiniband/hw/qib/qib_keys.c
+++ b/drivers/infiniband/hw/qib/qib_keys.c
@@ -34,42 +34,43 @@
#include "qib.h"

/**
* qib_alloc_lkey - allocate an lkey
* @mr: memory region that this lkey protects
* @dma_region: 0->normal key, 1->restricted DMA key
*
* Returns 0 if successful, otherwise returns -errno.
*
- * Increments mr reference count and sets published
- * as required.
+ * Increments mr reference count as required.
*
* Sets the lkey field mr for non-dma regions.
*
*/

int qib_alloc_lkey(struct qib_mregion *mr, int dma_region)
{
unsigned long flags;
u32 r;
u32 n;
int ret = 0;
struct qib_ibdev *dev = to_idev(mr->pd->device);
struct qib_lkey_table *rkt = &dev->lk_table;

spin_lock_irqsave(&rkt->lock, flags);

/* special case for dma_mr lkey == 0 */
if (dma_region) {
- /* should the dma_mr be relative to the pd? */
- if (!dev->dma_mr) {
+ struct qib_mregion *tmr;
+
+ tmr = rcu_dereference(dev->dma_mr);
+ if (!tmr) {
qib_get_mr(mr);
- dev->dma_mr = mr;
+ rcu_assign_pointer(dev->dma_mr, mr);
mr->lkey_published = 1;
}
goto success;
}

/* Find the next available LKEY */
r = rkt->next;
n = r;
for (;;) {
@@ -87,19 +88,19 @@ int qib_alloc_lkey(struct qib_mregion *mr, int dma_region)
rkt->gen++;
mr->lkey = (r << (32 - ib_qib_lkey_table_size)) |
((((1 << (24 - ib_qib_lkey_table_size)) - 1) & rkt->gen)
<< 8);
if (mr->lkey == 0) {
mr->lkey |= 1 << 8;
rkt->gen++;
}
qib_get_mr(mr);
- rkt->table[r] = mr;
+ rcu_assign_pointer(rkt->table[r], mr);
mr->lkey_published = 1;
success:
spin_unlock_irqrestore(&rkt->lock, flags);
out:
return ret;
bail:
spin_unlock_irqrestore(&rkt->lock, flags);
ret = -ENOMEM;
goto out;
@@ -114,91 +115,89 @@ void qib_free_lkey(struct qib_mregion *mr)
unsigned long flags;
u32 lkey = mr->lkey;
u32 r;
struct qib_ibdev *dev = to_idev(mr->pd->device);
struct qib_lkey_table *rkt = &dev->lk_table;

spin_lock_irqsave(&rkt->lock, flags);
if (!mr->lkey_published)
goto out;
- mr->lkey_published = 0;
-
-
- spin_lock_irqsave(&dev->lk_table.lock, flags);
- if (lkey == 0) {
- if (dev->dma_mr && dev->dma_mr == mr) {
- qib_put_mr(dev->dma_mr);
- dev->dma_mr = NULL;
- }
- } else {
+ if (lkey == 0)
+ rcu_assign_pointer(dev->dma_mr, NULL);
+ else {
r = lkey >> (32 - ib_qib_lkey_table_size);
- qib_put_mr(dev->dma_mr);
- rkt->table[r] = NULL;
+ rcu_assign_pointer(rkt->table[r], NULL);
}
+ qib_put_mr(mr);
+ mr->lkey_published = 0;
out:
- spin_unlock_irqrestore(&dev->lk_table.lock, flags);
+ spin_unlock_irqrestore(&rkt->lock, flags);
}

/**
* qib_lkey_ok - check IB SGE for validity and initialize
* @rkt: table containing lkey to check SGE against
+ * @pd: protection domain
* @isge: outgoing internal SGE
* @sge: SGE to check
* @acc: access flags
*
* Return 1 if valid and successful, otherwise returns 0.
*
+ * increments the reference count upon success
+ *
* Check the IB SGE for validity and initialize our internal version
* of it.
*/
int qib_lkey_ok(struct qib_lkey_table *rkt, struct qib_pd *pd,
struct qib_sge *isge, struct ib_sge *sge, int acc)
{
struct qib_mregion *mr;
unsigned n, m;
size_t off;
- unsigned long flags;

/*
* We use LKEY == zero for kernel virtual addresses
* (see qib_get_dma_mr and qib_dma.c).
*/
- spin_lock_irqsave(&rkt->lock, flags);
+ rcu_read_lock();
if (sge->lkey == 0) {
struct qib_ibdev *dev = to_idev(pd->ibpd.device);

if (pd->user)
goto bail;
- if (!dev->dma_mr)
+ mr = rcu_dereference(dev->dma_mr);
+ if (!mr)
+ goto bail;
+ if (unlikely(!atomic_inc_not_zero(&mr->refcount)))
goto bail;
- qib_get_mr(dev->dma_mr);
- spin_unlock_irqrestore(&rkt->lock, flags);
+ rcu_read_unlock();

- isge->mr = dev->dma_mr;
+ isge->mr = mr;
isge->vaddr = (void *) sge->addr;
isge->length = sge->length;
isge->sge_length = sge->length;
isge->m = 0;
isge->n = 0;
goto ok;
}
- mr = rkt->table[(sge->lkey >> (32 - ib_qib_lkey_table_size))];
- if (unlikely(mr == NULL || mr->lkey != sge->lkey ||
- mr->pd != &pd->ibpd))
+ mr = rcu_dereference(
+ rkt->table[(sge->lkey >> (32 - ib_qib_lkey_table_size))]);
+ if (unlikely(!mr || mr->lkey != sge->lkey || mr->pd != &pd->ibpd))
goto bail;

off = sge->addr - mr->user_base;
- if (unlikely(sge->addr < mr->user_base ||
- off + sge->length > mr->length ||
- (mr->access_flags & acc) != acc))
+ if (unlikely(sge->addr < mr->iova || off + sge->length > mr->length ||
+ (mr->access_flags & acc) == 0))
goto bail;
- qib_get_mr(mr);
- spin_unlock_irqrestore(&rkt->lock, flags);
+ if (unlikely(!atomic_inc_not_zero(&mr->refcount)))
+ goto bail;
+ rcu_read_unlock();

off += mr->offset;
if (mr->page_shift) {
/*
page sizes are uniform power of 2 so no loop is necessary
entries_spanned_by_off is the number of times the loop below
would have executed.
*/
size_t entries_spanned_by_off;
@@ -222,77 +221,82 @@ int qib_lkey_ok(struct qib_lkey_table *rkt, struct qib_pd *pd,
isge->mr = mr;
isge->vaddr = mr->map[m]->segs[n].vaddr + off;
isge->length = mr->map[m]->segs[n].length - off;
isge->sge_length = sge->length;
isge->m = m;
isge->n = n;
ok:
return 1;
bail:
- spin_unlock_irqrestore(&rkt->lock, flags);
+ rcu_read_unlock();
return 0;
}

/**
* qib_rkey_ok - check the IB virtual address, length, and RKEY
- * @dev: infiniband device
- * @ss: SGE state
+ * @qp: qp for validation
+ * @sge: SGE state
* @len: length of data
* @vaddr: virtual address to place data
* @rkey: rkey to check
* @acc: access flags
*
* Return 1 if successful, otherwise 0.
+ *
+ * increments the reference count upon success
*/
int qib_rkey_ok(struct qib_qp *qp, struct qib_sge *sge,
u32 len, u64 vaddr, u32 rkey, int acc)
{
struct qib_lkey_table *rkt = &to_idev(qp->ibqp.device)->lk_table;
struct qib_mregion *mr;
unsigned n, m;
size_t off;
- unsigned long flags;

/*
* We use RKEY == zero for kernel virtual addresses
* (see qib_get_dma_mr and qib_dma.c).
*/
- spin_lock_irqsave(&rkt->lock, flags);
+ rcu_read_lock();
if (rkey == 0) {
struct qib_pd *pd = to_ipd(qp->ibqp.pd);
struct qib_ibdev *dev = to_idev(pd->ibpd.device);

if (pd->user)
goto bail;
- if (!dev->dma_mr)
+ mr = rcu_dereference(dev->dma_mr);
+ if (!mr)
goto bail;
- qib_get_mr(dev->dma_mr);
- spin_unlock_irqrestore(&rkt->lock, flags);
+ if (unlikely(!atomic_inc_not_zero(&mr->refcount)))
+ goto bail;
+ rcu_read_unlock();

- sge->mr = dev->dma_mr;
+ sge->mr = mr;
sge->vaddr = (void *) vaddr;
sge->length = len;
sge->sge_length = len;
sge->m = 0;
sge->n = 0;
goto ok;
}

- mr = rkt->table[(rkey >> (32 - ib_qib_lkey_table_size))];
- if (unlikely(mr == NULL || mr->lkey != rkey || qp->ibqp.pd != mr->pd))
+ mr = rcu_dereference(
+ rkt->table[(rkey >> (32 - ib_qib_lkey_table_size))]);
+ if (unlikely(!mr || mr->lkey != rkey || qp->ibqp.pd != mr->pd))
goto bail;

off = vaddr - mr->iova;
if (unlikely(vaddr < mr->iova || off + len > mr->length ||
(mr->access_flags & acc) == 0))
goto bail;
- qib_get_mr(mr);
- spin_unlock_irqrestore(&rkt->lock, flags);
+ if (unlikely(!atomic_inc_not_zero(&mr->refcount)))
+ goto bail;
+ rcu_read_unlock();

off += mr->offset;
if (mr->page_shift) {
/*
page sizes are uniform power of 2 so no loop is necessary
entries_spanned_by_off is the number of times the loop below
would have executed.
*/
size_t entries_spanned_by_off;
@@ -316,19 +320,19 @@ int qib_rkey_ok(struct qib_qp *qp, struct qib_sge *sge,
sge->mr = mr;
sge->vaddr = mr->map[m]->segs[n].vaddr + off;
sge->length = mr->map[m]->segs[n].length - off;
sge->sge_length = len;
sge->m = m;
sge->n = n;
ok:
return 1;
bail:
- spin_unlock_irqrestore(&rkt->lock, flags);
+ rcu_read_unlock();
return 0;
}

/*
* Initialize the memory region specified by the work reqeust.
*/
int qib_fast_reg_mr(struct qib_qp *qp, struct ib_send_wr *wr)
{
struct qib_lkey_table *rkt = &to_idev(qp->ibqp.device)->lk_table;
diff --git a/drivers/infiniband/hw/qib/qib_mr.c b/drivers/infiniband/hw/qib/qib_mr.c
index 6a2028a..e6687de 100644
--- a/drivers/infiniband/hw/qib/qib_mr.c
+++ b/drivers/infiniband/hw/qib/qib_mr.c
@@ -521,9 +521,16 @@ int qib_dealloc_fmr(struct ib_fmr *ibfmr)
qib_get_mr(&fmr->mr);
ret = -EBUSY;
goto out;
}
deinit_qib_mregion(&fmr->mr);
kfree(fmr);
out:
return ret;
}
+
+void mr_rcu_callback(struct rcu_head *list)
+{
+ struct qib_mregion *mr = container_of(list, struct qib_mregion, list);
+
+ complete(&mr->comp);
+}
diff --git a/drivers/infiniband/hw/qib/qib_verbs.c b/drivers/infiniband/hw/qib/qib_verbs.c
index 76d7ce8..59cdea3 100644
--- a/drivers/infiniband/hw/qib/qib_verbs.c
+++ b/drivers/infiniband/hw/qib/qib_verbs.c
@@ -2060,19 +2060,21 @@ int qib_register_ib_device(struct qib_devdata *dd)
spin_lock_init(&dev->lk_table.lock);
dev->lk_table.max = 1 << ib_qib_lkey_table_size;
lk_tab_size = dev->lk_table.max * sizeof(*dev->lk_table.table);
dev->lk_table.table = (struct qib_mregion **)
__get_free_pages(GFP_KERNEL, get_order(lk_tab_size));
if (dev->lk_table.table == NULL) {
ret = -ENOMEM;
goto err_lk;
}
- memset(dev->lk_table.table, 0, lk_tab_size);
+ RCU_INIT_POINTER(dev->dma_mr, NULL);
+ for (i = 0; i < dev->lk_table.max; i++)
+ RCU_INIT_POINTER(dev->lk_table.table[i], NULL);
INIT_LIST_HEAD(&dev->pending_mmaps);
spin_lock_init(&dev->pending_lock);
dev->mmap_offset = PAGE_SIZE;
spin_lock_init(&dev->mmap_offset_lock);
INIT_LIST_HEAD(&dev->piowait);
INIT_LIST_HEAD(&dev->dmawait);
INIT_LIST_HEAD(&dev->txwait);
INIT_LIST_HEAD(&dev->memwait);
INIT_LIST_HEAD(&dev->txreq_free);
diff --git a/drivers/infiniband/hw/qib/qib_verbs.h b/drivers/infiniband/hw/qib/qib_verbs.h
index 4a2277b..85751fd 100644
--- a/drivers/infiniband/hw/qib/qib_verbs.h
+++ b/drivers/infiniband/hw/qib/qib_verbs.h
@@ -297,20 +297,21 @@ struct qib_mregion {
u64 user_base; /* User's address for this region */
u64 iova; /* IB start address of this region */
size_t length;
u32 lkey;
u32 offset; /* offset (bytes) to start of region */
int access_flags;
u32 max_segs; /* number of qib_segs in all the arrays */
u32 mapsz; /* size of the map array */
u8 page_shift; /* 0 - non unform/non powerof2 sizes */
- u8 lkey_published; /* in global table */
+ u8 lkey_published; /* in global table */
struct completion comp; /* complete when refcount goes to zero */
+ struct rcu_head list;
atomic_t refcount;
struct qib_segarray *map[0]; /* the segments */
};

/*
* These keep track of the copy progress within a memory region.
* Used by the verbs layer.
*/
struct qib_sge {
@@ -1016,22 +1017,24 @@ int qib_map_phys_fmr(struct ib_fmr *ibfmr, u64 *page_list,
int qib_unmap_fmr(struct list_head *fmr_list);

int qib_dealloc_fmr(struct ib_fmr *ibfmr);

static inline void qib_get_mr(struct qib_mregion *mr)
{
atomic_inc(&mr->refcount);
}

+void mr_rcu_callback(struct rcu_head *list);
+
static inline void qib_put_mr(struct qib_mregion *mr)
{
if (unlikely(atomic_dec_and_test(&mr->refcount)))
- complete(&mr->comp);
+ call_rcu(&mr->list, mr_rcu_callback);
}

static inline void qib_put_ss(struct qib_sge_state *ss)
{
while (ss->num_sge) {
qib_put_mr(ss->sge.mr);
if (--ss->num_sge)
ss->sge = *ss->sg_list++;
}
--
1.7.10