On Mon, Nov 8, 2010 at 10:47 AM, Arun R Bharadwaj
<a...@linux.vnet.ibm.com> wrote:
> diff --git a/hw/virtio-9p.c b/hw/virtio-9p.c
> index 7c59988..61b65fd 100644
> --- a/hw/virtio-9p.c
> +++ b/hw/virtio-9p.c
> @@ -18,6 +18,7 @@
> #include "fsdev/qemu-fsdev.h"
> #include "virtio-9p-debug.h"
> #include "virtio-9p-xattr.h"
> +#include "qemu-threadlets.h"
>
> int debug_9p_pdu;
>
> @@ -33,6 +34,146 @@ enum {
> Oappend = 0x80,
> };
>
> +struct v9fs_post_op {
> + QTAILQ_ENTRY(v9fs_post_op) node;
> + void (*func)(void *arg);
> + void *arg;
> +};
Structs are usually typedefed:
typedef struct V9fsPostOp {
...
} V9fsPostOp;
QEMU usually doesn't use struct explicitly unless a library interface
requires it.
> +
> +static struct {
> + int rfd;
> + int wfd;
> + QemuMutex lock;
> + QTAILQ_HEAD(, v9fs_post_op) post_op_list;
> +} v9fs_async_struct;
> +
> +static void die2(int err, const char *what)
> +{
> + fprintf(stderr, "%s failed: %s\n", what, strerror(err));
> + abort();
> +}
> +
> +static void die(const char *what)
> +{
> + die2(errno, what);
> +}
> +
> +#define ASYNC_MAX_PROCESS 5
> +
> +/**
> + * v9fs_process_post_ops: Process any pending v9fs_post_posix_operation
> + * @arg: Not used.
> + *
> + * This function serves as a callback to the iothread to be called into
> whenever
> + * the v9fs_async_struct.wfd is written into. This thread goes through the
> list
> + * of v9fs_post_posix_operations() and executes them. In the process, it
> might
> + * queue more job on the asynchronous thread pool.
> + */
> +static void v9fs_process_post_ops(void *arg)
> +{
> + int count = 0;
> + struct v9fs_post_op *post_op;
> + int ret;
> + char byte;
> +
> + qemu_mutex_lock(&v9fs_async_struct.lock);
> + do {
> + ret = read(v9fs_async_struct.rfd, &byte, sizeof(byte));
> + } while (ret >= 0 && errno != EAGAIN);
} while (ret > 1 || (ret == -1 && errno == EINTR)); ?
> +
> + for (count = 0; count < ASYNC_MAX_PROCESS; count++) {
> + if (QTAILQ_EMPTY(&(v9fs_async_struct.post_op_list))) {
> + break;
> + }
> + post_op = QTAILQ_FIRST(&(v9fs_async_struct.post_op_list));
> + QTAILQ_REMOVE(&(v9fs_async_struct.post_op_list), post_op, node);
> +
> + qemu_mutex_unlock(&v9fs_async_struct.lock);
> + post_op->func(post_op->arg);
> + qemu_free(post_op);
> + qemu_mutex_lock(&v9fs_async_struct.lock);
> + }
> + qemu_mutex_unlock(&v9fs_async_struct.lock);
> +}
> +
> +/**
> + * v9fs_async_signal: Inform the io-thread of completion of async job.
> + *
> + * This function is used to inform the iothread that a particular
> + * async-operation pertaining to v9fs has been completed and that the io
> thread
> + * can handle the v9fs_post_posix_operation.
> + *
> + * This is based on the aio_signal_handler
> + */
> +static inline void v9fs_async_signal(void)
> +{
> + char byte = 0;
> + ssize_t ret;
> + int tries = 0;
> +
> + qemu_mutex_lock(&v9fs_async_struct.lock);
> + do {
> + assert(tries != 100);
> + ret = write(v9fs_async_struct.wfd, &byte, sizeof(byte));
> + tries++;
> + } while (ret < 0 && errno == EAGAIN);
> + qemu_mutex_unlock(&v9fs_async_struct.lock);
> +
> + if (ret < 0 && errno != EAGAIN)
> + die("write() in v9fs");
{ } coding style
> +
> + if (kill(getpid(), SIGUSR2)) die("kill failed");
{ } coding style
> +}
> +
> +/**
> + * v9fs_async_helper_done: Marks the completion of the v9fs_async job
> + * @func: v9fs_post_posix_func() for post-processing invoked in the context
> of
> + * the io-thread
> + * @arg: Argument to func.
> + *
> + * This function is called from the context of one of the asynchronous
> threads
> + * in the thread pool. This is called when the asynchronous thread has
> finished
> + * executing a v9fs_posix_operation. It's purpose is to initiate the process
> of
> + * informing the io-thread that the v9fs_posix_operation has completed.
> + */
> +static void v9fs_async_helper_done(void (*func)(void *arg), void *arg)
> +{
> + struct v9fs_post_op *post_op;
> +
> + post_op = qemu_mallocz(sizeof(*post_op));
> + post_op->func = func;
> + post_op->arg = arg;
> +
> + qemu_mutex_lock(&v9fs_async_struct.lock);
> + QTAILQ_INSERT_TAIL(&(v9fs_async_struct.post_op_list), post_op, node);
> + qemu_mutex_unlock(&v9fs_async_struct.lock);
> +
> + v9fs_async_signal();
> +}
> +
> +/**
> + * v9fs_do_async_posix: Offload v9fs_posix_operation onto async thread.
> + * @vs: V9fsOPState variable for the OP operation.
> + * @posix_fn: The posix function which has to be offloaded onto async thread.
> + * @post_fn_ptr: Address of the location to hold the post_fn corresponding to
> + * the posix_fn
> + * @post_fn: The post processing function corresponding to the posix_fn.
> + *
> + * This function is a helper to offload posix_operation on to the
> asynchronous
> + * thread pool. It sets up the associations with the post_function that
> needs to
> + * be invoked by from the context of the iothread once the posix_fn has been
> + * executed.
> + */
> +static void v9fs_do_async_posix(ThreadletWork *work ,
> + void (*posix_fn)(ThreadletWork *work),
> + void (**post_fn_ptr)(void *arg),
> + void (*post_fn)(void *arg))
> +{
> + *post_fn_ptr = post_fn;
> + work->func = posix_fn;
> + submit_work(work);
> +}
> +
> static int omode_to_uflags(int8_t mode)
> {
> int ret = 0;
> @@ -3657,7 +3798,7 @@ VirtIODevice *virtio_9p_init(DeviceState *dev, V9fsConf
> *conf)
> int i, len;
> struct stat stat;
> FsTypeEntry *fse;
> -
> + int fds[2];
>
> s = (V9fsState *)virtio_common_init("virtio-9p",
> VIRTIO_ID_9P,
> @@ -3740,5 +3881,27 @@ VirtIODevice *virtio_9p_init(DeviceState *dev,
> V9fsConf *conf)
> s->tag_len;
> s->vdev.get_config = virtio_9p_get_config;
>
> + if (qemu_pipe(fds) == -1) {
> + fprintf(stderr, "failed to create fd's for virtio-9p\n");
> + exit(1);
> + }
> +
> + v9fs_async_struct.rfd = fds[0];
> + v9fs_async_struct.wfd = fds[1];
> +
> + printf("v9fs: rfd: %d\n", v9fs_async_struct.rfd);
> + printf("v9fs: wfd: %d\n", v9fs_async_struct.wfd);
> +
> + fcntl(fds[0], F_SETFL, O_NONBLOCK);
> + fcntl(fds[1], F_SETFL, O_NONBLOCK);
> +
> + 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));
> + /* Create async queue. */
Please delete this comment, it seems outdated.
> +
> + (void)v9fs_do_async_posix;
> + (void)v9fs_async_helper_done;
> +
> return &s->vdev;
> }
> diff --git a/posix-aio-compat.c b/posix-aio-compat.c
> index 9e02d18..8019be7 100644
> --- a/posix-aio-compat.c
> +++ b/posix-aio-compat.c
> @@ -260,6 +260,8 @@ static ssize_t handle_aiocb_rw(struct qemu_paiocb *aiocb)
> return nbytes;
> }
>
> +static PosixAioState *posix_aio_state;
> +
> static void aio_thread(ThreadletWork *work)
> {
> pid_t pid;
> @@ -290,6 +292,15 @@ static void aio_thread(ThreadletWork *work)
> aiocb->ret = ret;
> qemu_mutex_unlock(&aiocb_mutex);
>
> + if (posix_aio_state) {
This test is not needed because posix_aio_state must be non-NULL here.
> + char byte = 0;
> + ssize_t ret;
> +
> + ret = write(posix_aio_state->wfd, &byte, sizeof(byte));
> + if (ret < 0 && errno != EAGAIN)
Please always use if () { ... } curly braces. QEMU coding style.
Stefan
