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[Qemu-devel] [PATCH 2/9] Introduce lock fid_list_lock to protect the fid
From: |
Arun R Bharadwaj |
Subject: |
[Qemu-devel] [PATCH 2/9] Introduce lock fid_list_lock to protect the fid list. |
Date: |
Thu, 14 Oct 2010 17:53:48 +0530 |
User-agent: |
StGit/0.15 |
From: Sripathi Kodi <address@hidden>
Currently it is a normal mutex, but I will change it into a rw mutex.
This should be held in read mode while looking up and in write mode
while updating the list.
Signed-off-by: Sripathi Kodi <address@hidden>
---
hw/virtio-9p.c | 32 +++++++++++++++++++++++++++++---
hw/virtio-9p.h | 2 ++
2 files changed, 31 insertions(+), 3 deletions(-)
diff --git a/hw/virtio-9p.c b/hw/virtio-9p.c
index 174300d..02a4ec4 100644
--- a/hw/virtio-9p.c
+++ b/hw/virtio-9p.c
@@ -18,7 +18,6 @@
#include "fsdev/qemu-fsdev.h"
#include "virtio-9p-debug.h"
#include "virtio-9p-xattr.h"
-#include "qemu-threadlets.h"
int debug_9p_pdu;
@@ -552,7 +551,8 @@ static size_t v9fs_string_size(V9fsString *str)
return str->size;
}
-static V9fsFidState *lookup_fid(V9fsState *s, int32_t fid)
+/* fid_list_lock should be held on entry */
+static V9fsFidState *__lookup_fid(V9fsState *s, int32_t fid)
{
V9fsFidState *f;
@@ -565,12 +565,26 @@ static V9fsFidState *lookup_fid(V9fsState *s, int32_t fid)
return NULL;
}
+static V9fsFidState *lookup_fid(V9fsState *s, int32_t fid)
+{
+ V9fsFidState *f;
+
+ qemu_rwmutex_rdlock(&s->fid_list_lock);
+ f = __lookup_fid(s, fid);
+ qemu_rwmutex_unlock(&s->fid_list_lock);
+
+ return f;
+}
+
+
static V9fsFidState *alloc_fid(V9fsState *s, int32_t fid)
{
V9fsFidState *f;
- f = lookup_fid(s, fid);
+ qemu_rwmutex_wrlock(&s->fid_list_lock);
+ f = __lookup_fid(s, fid);
if (f) {
+ qemu_rwmutex_unlock(&s->fid_list_lock);
return NULL;
}
@@ -582,6 +596,7 @@ static V9fsFidState *alloc_fid(V9fsState *s, int32_t fid)
f->next = s->fid_list;
s->fid_list = f;
+ qemu_rwmutex_unlock(&(s->fid_list_lock));
return f;
}
@@ -619,11 +634,13 @@ free_value:
return retval;
}
+/* On entry, fid_list_lock and fid_lock should NOT be held */
static int free_fid(V9fsState *s, int32_t fid)
{
int retval = 0;
V9fsFidState **fidpp, *fidp;
+ qemu_rwmutex_wrlock(&s->fid_list_lock);
for (fidpp = &s->fid_list; *fidpp; fidpp = &(*fidpp)->next) {
if ((*fidpp)->fid == fid) {
break;
@@ -631,12 +648,18 @@ static int free_fid(V9fsState *s, int32_t fid)
}
if (*fidpp == NULL) {
+ qemu_rwmutex_unlock(&s->fid_list_lock);
return -ENOENT;
}
fidp = *fidpp;
*fidpp = fidp->next;
+ /* We have removed the node from the list, so we can release
+ * the fid_list_lock now
+ */
+ qemu_rwmutex_unlock(&s->fid_list_lock);
+
if (fidp->fid_type == P9_FID_FILE) {
v9fs_do_close(s, fidp->fs.fd);
} else if (fidp->fid_type == P9_FID_DIR) {
@@ -2922,6 +2945,7 @@ static int v9fs_complete_rename(V9fsState *s,
V9fsRenameState *vs)
* Fixup fid's pointing to the old name to
* start pointing to the new name
*/
+ qemu_rwmutex_rdlock(&s->fid_list_lock);
for (fidp = s->fid_list; fidp; fidp = fidp->next) {
if (vs->fidp == fidp) {
/*
@@ -2937,6 +2961,7 @@ static int v9fs_complete_rename(V9fsState *s,
V9fsRenameState *vs)
strlen(vs->fidp->path.data));
}
}
+ qemu_rwmutex_unlock(&s->fid_list_lock);
v9fs_string_copy(&vs->fidp->path, &vs->name);
}
}
@@ -3880,6 +3905,7 @@ VirtIODevice *virtio_9p_init(DeviceState *dev, V9fsConf
*conf)
qemu_set_fd_handler(fds[0], v9fs_process_post_ops, NULL, NULL);
QTAILQ_INIT(&v9fs_async_struct.post_op_list);
qemu_mutex_init(&(v9fs_async_struct.lock));
+ qemu_rwmutex_init(&(s->fid_list_lock));
/* Create async queue. */
(void)v9fs_do_async_posix;
diff --git a/hw/virtio-9p.h b/hw/virtio-9p.h
index 6c23319..f58d3d8 100644
--- a/hw/virtio-9p.h
+++ b/hw/virtio-9p.h
@@ -7,6 +7,7 @@
#include <utime.h>
#include "file-op-9p.h"
+#include "qemu-threadlets.h"
/* The feature bitmap for virtio 9P */
/* The mount point is specified in a config variable */
@@ -206,6 +207,7 @@ typedef struct V9fsState
V9fsPDU pdus[MAX_REQ];
QLIST_HEAD(, V9fsPDU) free_list;
V9fsFidState *fid_list;
+ QemuRWMutex fid_list_lock;
FileOperations *ops;
FsContext ctx;
uint16_t tag_len;
- [Qemu-devel] [RFC PATCH 0/9] Second threading model., Arun R Bharadwaj, 2010/10/14
- [Qemu-devel] [PATCH 1/9] Add read-write lock to QEMU, Arun R Bharadwaj, 2010/10/14
- [Qemu-devel] [PATCH 2/9] Introduce lock fid_list_lock to protect the fid list.,
Arun R Bharadwaj <=
- [Qemu-devel] [PATCH 3/9] Global rename lock, Arun R Bharadwaj, 2010/10/14
- [Qemu-devel] [PATCH 4/9] Convert stat into 2nd threading model, Arun R Bharadwaj, 2010/10/14
- [Qemu-devel] [PATCH 5/9] Convert wstat into 2nd threading model, Arun R Bharadwaj, 2010/10/14
- [Qemu-devel] [PATCH 6/9] Convert open into 2nd threading model, Arun R Bharadwaj, 2010/10/14
- [Qemu-devel] [PATCH 7/9] Convert walk into 2nd threading model, Arun R Bharadwaj, 2010/10/14
- [Qemu-devel] [PATCH 8/9] Convert read into 2nd threading model, Arun R Bharadwaj, 2010/10/14
- [Qemu-devel] [PATCH 9/9] Convert write into 2nd threading model., Arun R Bharadwaj, 2010/10/14