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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 05/10] xen: use SMP barrier in common code dealing with shared memory protocols
Xen currently makes no strong distinction between the SMP barriers (smp_mb
etc) and the regular barrier (mb etc). In Linux, where we inherited these
names from having imported Linux code which uses them, the SMP barriers are
intended to be sufficient for implementing shared-memory protocols between
processors in an SMP system while the standard barriers are useful for MMIO
etc.
On x86 with the stronger ordering model there is not much practical difference
here but ARM has weaker barriers available which are suitable for use as SMP
barriers.
Therefore ensure that common code uses the SMP barriers when that is all which
is required.
On both ARM and x86 both types of barrier are currently identical so there is
no actual change. A future patch will change smp_mb to a weaker barrier on
ARM.
Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: jbeuich@xxxxxxxx
Cc: keir@xxxxxxx
---
I'm not convinced some of these mb() couldn't actually be wmb(), but I didn't
think to hard about this or make any changes along those lines.
---
xen/common/domain.c | 2 +-
xen/common/domctl.c | 2 +-
xen/common/grant_table.c | 4 ++--
xen/common/page_alloc.c | 2 +-
xen/common/smp.c | 4 ++--
xen/common/spinlock.c | 6 +++---
xen/common/tmem_xen.c | 10 +++++-----
xen/common/trace.c | 8 ++++----
xen/drivers/char/console.c | 2 +-
xen/include/xen/event.h | 4 ++--
xen/xsm/flask/ss/sidtab.c | 4 ++--
11 files changed, 24 insertions(+), 24 deletions(-)
diff --git a/xen/common/domain.c b/xen/common/domain.c
index fac3470..1380ea9 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -932,7 +932,7 @@ int map_vcpu_info(struct vcpu *v, unsigned long gfn,
unsigned offset)
v->vcpu_info_mfn = page_to_mfn(page);
/* Set new vcpu_info pointer /before/ setting pending flags. */
- wmb();
+ smp_wmb();
/*
* Mark everything as being pending just to make sure nothing gets
diff --git a/xen/common/domctl.c b/xen/common/domctl.c
index 9bd8f80..c653efb 100644
--- a/xen/common/domctl.c
+++ b/xen/common/domctl.c
@@ -533,7 +533,7 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t)
u_domctl)
/* Install vcpu array /then/ update max_vcpus. */
d->vcpu = vcpus;
- wmb();
+ smp_wmb();
d->max_vcpus = max;
}
diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c
index 3f97328..eb50288 100644
--- a/xen/common/grant_table.c
+++ b/xen/common/grant_table.c
@@ -426,7 +426,7 @@ static int _set_status_v2(domid_t domid,
/* Make sure guest sees status update before checking if flags are
still valid */
- mb();
+ smp_mb();
scombo.word = *(u32 *)shah;
barrier();
@@ -1670,7 +1670,7 @@ gnttab_transfer(
guest_physmap_add_page(e, sha->full_page.frame, mfn, 0);
sha->full_page.frame = mfn;
}
- wmb();
+ smp_wmb();
shared_entry_header(e->grant_table, gop.ref)->flags |=
GTF_transfer_completed;
diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index 2162ef1..25a7d3d 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -1472,7 +1472,7 @@ int assign_pages(
ASSERT(page_get_owner(&pg[i]) == NULL);
ASSERT((pg[i].count_info & ~(PGC_allocated | 1)) == 0);
page_set_owner(&pg[i], d);
- wmb(); /* Domain pointer must be visible before updating refcnt. */
+ smp_wmb(); /* Domain pointer must be visible before updating refcnt. */
pg[i].count_info = PGC_allocated | 1;
page_list_add_tail(&pg[i], &d->page_list);
}
diff --git a/xen/common/smp.c b/xen/common/smp.c
index b2b056b..482a203 100644
--- a/xen/common/smp.c
+++ b/xen/common/smp.c
@@ -89,12 +89,12 @@ void smp_call_function_interrupt(void)
if ( call_data.wait )
{
(*func)(info);
- mb();
+ smp_mb();
cpumask_clear_cpu(cpu, &call_data.selected);
}
else
{
- mb();
+ smp_mb();
cpumask_clear_cpu(cpu, &call_data.selected);
(*func)(info);
}
diff --git a/xen/common/spinlock.c b/xen/common/spinlock.c
index bfb9670..575cc6d 100644
--- a/xen/common/spinlock.c
+++ b/xen/common/spinlock.c
@@ -218,7 +218,7 @@ void _spin_barrier(spinlock_t *lock)
u64 loop = 0;
check_barrier(&lock->debug);
- do { mb(); loop++;} while ( _raw_spin_is_locked(&lock->raw) );
+ do { smp_mb(); loop++;} while ( _raw_spin_is_locked(&lock->raw) );
if ((loop > 1) && lock->profile)
{
lock->profile->time_block += NOW() - block;
@@ -226,9 +226,9 @@ void _spin_barrier(spinlock_t *lock)
}
#else
check_barrier(&lock->debug);
- do { mb(); } while ( _raw_spin_is_locked(&lock->raw) );
+ do { smp_mb(); } while ( _raw_spin_is_locked(&lock->raw) );
#endif
- mb();
+ smp_mb();
}
int _spin_trylock_recursive(spinlock_t *lock)
diff --git a/xen/common/tmem_xen.c b/xen/common/tmem_xen.c
index 736a8c3..54ec09f 100644
--- a/xen/common/tmem_xen.c
+++ b/xen/common/tmem_xen.c
@@ -173,7 +173,7 @@ EXPORT int tmh_copy_from_client(pfp_t *pfp,
return -EFAULT;
}
}
- mb();
+ smp_mb();
if ( len == PAGE_SIZE && !tmem_offset && !pfn_offset && cli_va )
tmh_copy_page(tmem_va, cli_va);
else if ( (tmem_offset+len <= PAGE_SIZE) &&
@@ -216,7 +216,7 @@ EXPORT int tmh_compress_from_client(tmem_cli_mfn_t cmfn,
return 0;
else if ( copy_from_guest(scratch, clibuf, PAGE_SIZE) )
return -EFAULT;
- mb();
+ smp_mb();
ret = lzo1x_1_compress(cli_va ?: scratch, PAGE_SIZE, dmem, out_len, wmem);
ASSERT(ret == LZO_E_OK);
*out_va = dmem;
@@ -260,7 +260,7 @@ EXPORT int tmh_copy_to_client(tmem_cli_mfn_t cmfn, pfp_t
*pfp,
unmap_domain_page(tmem_va);
if ( cli_va )
cli_put_page(cli_va, cli_pfp, cli_mfn, 1);
- mb();
+ smp_mb();
return rc;
}
@@ -289,7 +289,7 @@ EXPORT int tmh_decompress_to_client(tmem_cli_mfn_t cmfn,
void *tmem_va,
cli_put_page(cli_va, cli_pfp, cli_mfn, 1);
else if ( copy_to_guest(clibuf, scratch, PAGE_SIZE) )
return -EFAULT;
- mb();
+ smp_mb();
return 1;
}
@@ -311,7 +311,7 @@ EXPORT int tmh_copy_tze_to_client(tmem_cli_mfn_t cmfn, void
*tmem_va,
if ( len < PAGE_SIZE )
memset((char *)cli_va+len,0,PAGE_SIZE-len);
cli_put_page(cli_va, cli_pfp, cli_mfn, 1);
- mb();
+ smp_mb();
return 1;
}
diff --git a/xen/common/trace.c b/xen/common/trace.c
index fd4ac48..63ea0b7 100644
--- a/xen/common/trace.c
+++ b/xen/common/trace.c
@@ -255,7 +255,7 @@ static int alloc_trace_bufs(unsigned int pages)
opt_tbuf_size = pages;
printk("xentrace: initialised\n");
- wmb(); /* above must be visible before tb_init_done flag set */
+ smp_wmb(); /* above must be visible before tb_init_done flag set */
tb_init_done = 1;
return 0;
@@ -414,7 +414,7 @@ int tb_control(xen_sysctl_tbuf_op_t *tbc)
int i;
tb_init_done = 0;
- wmb();
+ smp_wmb();
/* Clear any lost-record info so we don't get phantom lost records
next time we
* start tracing. Grab the lock to make sure we're not racing anyone.
After this
* hypercall returns, no more records should be placed into the
buffers. */
@@ -607,7 +607,7 @@ static inline void __insert_record(struct t_buf *buf,
memcpy(next_page, (char *)rec + remaining, rec_size - remaining);
}
- wmb();
+ smp_wmb();
next += rec_size;
if ( next >= 2*data_size )
@@ -718,7 +718,7 @@ void __trace_var(u32 event, bool_t cycles, unsigned int
extra,
return;
/* Read tb_init_done /before/ t_bufs. */
- rmb();
+ smp_rmb();
spin_lock_irqsave(&this_cpu(t_lock), flags);
diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
index 7cd7bf6..b696b3e 100644
--- a/xen/drivers/char/console.c
+++ b/xen/drivers/char/console.c
@@ -648,7 +648,7 @@ void __init console_init_postirq(void)
for ( i = conringc ; i != conringp; i++ )
ring[i & (opt_conring_size - 1)] = conring[i & (conring_size - 1)];
conring = ring;
- wmb(); /* Allow users of console_force_unlock() to see larger buffer. */
+ smp_wmb(); /* Allow users of console_force_unlock() to see larger buffer.
*/
conring_size = opt_conring_size;
spin_unlock_irq(&console_lock);
diff --git a/xen/include/xen/event.h b/xen/include/xen/event.h
index 4ac39ad..6f60162 100644
--- a/xen/include/xen/event.h
+++ b/xen/include/xen/event.h
@@ -85,7 +85,7 @@ void notify_via_xen_event_channel(struct domain *ld, int
lport);
if ( condition ) \
break; \
set_bit(_VPF_blocked_in_xen, ¤t->pause_flags); \
- mb(); /* set blocked status /then/ re-evaluate condition */ \
+ smp_mb(); /* set blocked status /then/ re-evaluate condition */ \
if ( condition ) \
{ \
clear_bit(_VPF_blocked_in_xen, ¤t->pause_flags); \
@@ -99,7 +99,7 @@ void notify_via_xen_event_channel(struct domain *ld, int
lport);
do { \
set_bit(_VPF_blocked_in_xen, ¤t->pause_flags); \
raise_softirq(SCHEDULE_SOFTIRQ); \
- mb(); /* set blocked status /then/ caller does his work */ \
+ smp_mb(); /* set blocked status /then/ caller does his work */ \
} while ( 0 )
#endif /* __XEN_EVENT_H__ */
diff --git a/xen/xsm/flask/ss/sidtab.c b/xen/xsm/flask/ss/sidtab.c
index 586033c..cd1360c 100644
--- a/xen/xsm/flask/ss/sidtab.c
+++ b/xen/xsm/flask/ss/sidtab.c
@@ -79,13 +79,13 @@ int sidtab_insert(struct sidtab *s, u32 sid, struct context
*context)
if ( prev )
{
newnode->next = prev->next;
- wmb();
+ smp_wmb();
prev->next = newnode;
}
else
{
newnode->next = s->htable[hvalue];
- wmb();
+ smp_wmb();
s->htable[hvalue] = newnode;
}
--
1.7.2.5
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