Re: [PATCH 6/6] kvm tools: Protect IOPORT tree by rwsem

[Sasha Levin]

On Thu, 2011-05-26 at 19:01 +0300, Pekka Enberg wrote:
> On Thu, 26 May 2011, Sasha Levin wrote:
> > Makes ioport thread-safe.
> >
> > Signed-off-by: Sasha Levin 
> > ---
> > tools/kvm/ioport.c |7 +++
> > 1 files changed, 7 insertions(+), 0 deletions(-)
> >
> > diff --git a/tools/kvm/ioport.c b/tools/kvm/ioport.c
> > index 1f13960..db9ff0f 100644
> > --- a/tools/kvm/ioport.c
> > +++ b/tools/kvm/ioport.c
> > @@ -3,6 +3,7 @@
> > #include "kvm/kvm.h"
> > #include "kvm/util.h"
> > #include "kvm/rbtree-interval.h"
> > +#include "kvm/rwsem.h"
> >
> > #include   /* for KVM_EXIT_* */
> > #include 
> > @@ -22,6 +23,7 @@ struct ioport_entry {
> >
> > static struct rb_root ioport_tree = RB_ROOT;
> > bool ioport_debug;
> > +static DECLARE_RWSEM(ioport_tree_sem);
> 
> Why do we need a new lock here? Can't we reuse the new ioport_mutex?

ioport_mutex is used for allocations of ioports to devices, this lock is
intended to protect the ioport tree from being read while new devices
are added.

-- 

Sasha.

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Re: [PATCH 6/6] kvm tools: Protect IOPORT tree by rwsem

[Pekka Enberg]

On Thu, 26 May 2011, Sasha Levin wrote:

Makes ioport thread-safe.

Signed-off-by: Sasha Levin 
---
tools/kvm/ioport.c |7 +++
1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/tools/kvm/ioport.c b/tools/kvm/ioport.c
index 1f13960..db9ff0f 100644
--- a/tools/kvm/ioport.c
+++ b/tools/kvm/ioport.c
@@ -3,6 +3,7 @@
#include "kvm/kvm.h"
#include "kvm/util.h"
#include "kvm/rbtree-interval.h"
+#include "kvm/rwsem.h"

#include /* for KVM_EXIT_* */
#include 
@@ -22,6 +23,7 @@ struct ioport_entry {

static struct rb_root ioport_tree = RB_ROOT;
bool ioport_debug;
+static DECLARE_RWSEM(ioport_tree_sem);


Why do we need a new lock here? Can't we reuse the new ioport_mutex?

Pekka
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[PATCH 6/6] kvm tools: Protect IOPORT tree by rwsem

[Sasha Levin]

Makes ioport thread-safe.

Signed-off-by: Sasha Levin 
---
 tools/kvm/ioport.c |7 +++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/tools/kvm/ioport.c b/tools/kvm/ioport.c
index 1f13960..db9ff0f 100644
--- a/tools/kvm/ioport.c
+++ b/tools/kvm/ioport.c
@@ -3,6 +3,7 @@
 #include "kvm/kvm.h"
 #include "kvm/util.h"
 #include "kvm/rbtree-interval.h"
+#include "kvm/rwsem.h"
 
 #include  /* for KVM_EXIT_* */
 #include 
@@ -22,6 +23,7 @@ struct ioport_entry {
 
 static struct rb_root ioport_tree = RB_ROOT;
 bool ioport_debug;
+static DECLARE_RWSEM(ioport_tree_sem);
 
 static struct ioport_entry *ioport_search(struct rb_root *root, u64 addr)
 {
@@ -71,6 +73,7 @@ void ioport__register(u16 port, struct ioport_operations 
*ops, int count)
 {
struct ioport_entry *entry;
 
+   down_write(&ioport_tree_sem);
entry = ioport_search(&ioport_tree, port);
if (entry) {
pr_warning("ioport re-registered: %x", port);
@@ -87,6 +90,8 @@ void ioport__register(u16 port, struct ioport_operations 
*ops, int count)
};
 
ioport_insert(&ioport_tree, entry);
+
+   up_write(&ioport_tree_sem);
 }
 
 static const char *to_direction(int direction)
@@ -108,7 +113,9 @@ bool kvm__emulate_io(struct kvm *kvm, u16 port, void *data, 
int direction, int s
bool ret;
struct ioport_entry *entry;
 
+   down_read(&ioport_tree_sem);
entry = ioport_search(&ioport_tree, port);
+   up_read(&ioport_tree_sem);
if (!entry)
goto error;
 
-- 
1.7.5.rc3

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