From: Sripathi Kodi <sripat...@in.ibm.com> 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 <sripat...@in.ibm.com> --- 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;