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Re: [Qemu-block] [PATCH v3 1/2] linux-aio: properly bubble up errors fro
From: |
Fam Zheng |
Subject: |
Re: [Qemu-block] [PATCH v3 1/2] linux-aio: properly bubble up errors from initialization |
Date: |
Fri, 22 Jun 2018 10:21:19 +0800 |
User-agent: |
Mutt/1.10.0 (2018-05-17) |
On Thu, 06/21 15:21, Nishanth Aravamudan wrote:
> laio_init() can fail for a couple of reasons, which will lead to a NULL
> pointer dereference in laio_attach_aio_context().
>
> To solve this, add a aio_setup_linux_aio() function which is called
> early in raw_open_common. If this fails, propagate the error up. The
> signature of aio_get_linux_aio() was not modified, because it seems
> preferable to return the actual errno from the possible failing
> initialization calls.
>
> Add an assert that aio_get_linux_aio() cannot return NULL.
>
> Signed-off-by: Nishanth Aravamudan <address@hidden>
> ---
> Changes from v2 -> v3 (thanks to Eric Blake and Kevin Wolf for review):
>
> Use a boolean false rather than 0 in assignment to use_linux_aio.
> Drop ending '.' from error_report() calls.
> Fix typo in commit message (propogates -> propagates).
> Move aio_setup_linux_aio call to raw_open_common.
>
> Changes from v1 -> v2 (thanks to Kevin Wolf for review):
>
> Rather than affect virtio-scsi/blk at all, make all the changes internal
> to file-posix.c. Thanks to Kevin Wolf for the suggested change.
>
> block/file-posix.c | 17 ++++++++++++-----
> block/linux-aio.c | 15 ++++++++++-----
> include/block/aio.h | 3 +++
> include/block/raw-aio.h | 2 +-
> stubs/linux-aio.c | 2 +-
> util/async.c | 16 +++++++++++++---
> 6 files changed, 40 insertions(+), 15 deletions(-)
>
> diff --git a/block/file-posix.c b/block/file-posix.c
> index 07bb061fe4..6a1714d4a8 100644
> --- a/block/file-posix.c
> +++ b/block/file-posix.c
> @@ -545,11 +545,18 @@ static int raw_open_common(BlockDriverState *bs, QDict
> *options,
>
> #ifdef CONFIG_LINUX_AIO
> /* Currently Linux does AIO only for files opened with O_DIRECT */
> - if (s->use_linux_aio && !(s->open_flags & O_DIRECT)) {
> - error_setg(errp, "aio=native was specified, but it requires "
> - "cache.direct=on, which was not specified.");
> - ret = -EINVAL;
> - goto fail;
> + if (s->use_linux_aio) {
> + if (!(s->open_flags & O_DIRECT)) {
> + error_setg(errp, "aio=native was specified, but it requires "
> + "cache.direct=on, which was not specified.");
> + ret = -EINVAL;
> + goto fail;
> + }
> + ret = aio_setup_linux_aio(bdrv_get_aio_context(bs));
> + if (ret != 0) {
> + error_setg(errp, "Unable to setup native AIO context.");
> + goto fail;
> + }
> }
> #else
> if (s->use_linux_aio) {
> diff --git a/block/linux-aio.c b/block/linux-aio.c
> index 88b8d55ec7..4d799f85fe 100644
> --- a/block/linux-aio.c
> +++ b/block/linux-aio.c
> @@ -470,28 +470,33 @@ void laio_attach_aio_context(LinuxAioState *s,
> AioContext *new_context)
> qemu_laio_poll_cb);
> }
>
> -LinuxAioState *laio_init(void)
> +int laio_init(LinuxAioState **linux_aio)
> {
> + int rc;
> LinuxAioState *s;
>
> s = g_malloc0(sizeof(*s));
> - if (event_notifier_init(&s->e, false) < 0) {
> + rc = event_notifier_init(&s->e, false);
> + if (rc < 0) {
It would be nice if the error message could distinguish this error...
> goto out_free_state;
> }
>
> - if (io_setup(MAX_EVENTS, &s->ctx) != 0) {
> + rc = io_setup(MAX_EVENTS, &s->ctx);
> + if (rc != 0) {
... from this one. And it also makes sense to propagate the errno back with
error_setg_errno.
To do this, add an "Error **errp" parameter to the function and you can keep the
return type (LinuxAioState *).
> goto out_close_efd;
> }
>
> ioq_init(&s->io_q);
>
> - return s;
> + *linux_aio = s;
> + return 0;
>
> out_close_efd:
> event_notifier_cleanup(&s->e);
> out_free_state:
> g_free(s);
> - return NULL;
> + *linux_aio = NULL;
> + return rc;
> }
>
> void laio_cleanup(LinuxAioState *s)
> diff --git a/include/block/aio.h b/include/block/aio.h
> index ae6f354e6c..8900516ac5 100644
> --- a/include/block/aio.h
> +++ b/include/block/aio.h
> @@ -381,6 +381,9 @@ GSource *aio_get_g_source(AioContext *ctx);
> /* Return the ThreadPool bound to this AioContext */
> struct ThreadPool *aio_get_thread_pool(AioContext *ctx);
>
> +/* Setup the LinuxAioState bound to this AioContext */
> +int aio_setup_linux_aio(AioContext *ctx);
And this will then need "Error **errp" as well.
> +
> /* Return the LinuxAioState bound to this AioContext */
> struct LinuxAioState *aio_get_linux_aio(AioContext *ctx);
>
> diff --git a/include/block/raw-aio.h b/include/block/raw-aio.h
> index 0e717fd475..81b90e5fc6 100644
> --- a/include/block/raw-aio.h
> +++ b/include/block/raw-aio.h
> @@ -43,7 +43,7 @@
> /* linux-aio.c - Linux native implementation */
> #ifdef CONFIG_LINUX_AIO
> typedef struct LinuxAioState LinuxAioState;
> -LinuxAioState *laio_init(void);
> +int laio_init(LinuxAioState **linux_aio);
> void laio_cleanup(LinuxAioState *s);
> int coroutine_fn laio_co_submit(BlockDriverState *bs, LinuxAioState *s, int
> fd,
> uint64_t offset, QEMUIOVector *qiov, int
> type);
> diff --git a/stubs/linux-aio.c b/stubs/linux-aio.c
> index ed47bd443c..88ab927e35 100644
> --- a/stubs/linux-aio.c
> +++ b/stubs/linux-aio.c
> @@ -21,7 +21,7 @@ void laio_attach_aio_context(LinuxAioState *s, AioContext
> *new_context)
> abort();
> }
>
> -LinuxAioState *laio_init(void)
> +int laio_init(LinuxAioState **linux_aio)
> {
> abort();
> }
> diff --git a/util/async.c b/util/async.c
> index 03f62787f2..ae88c931d0 100644
> --- a/util/async.c
> +++ b/util/async.c
> @@ -323,12 +323,22 @@ ThreadPool *aio_get_thread_pool(AioContext *ctx)
> }
>
> #ifdef CONFIG_LINUX_AIO
> -LinuxAioState *aio_get_linux_aio(AioContext *ctx)
> +int aio_setup_linux_aio(AioContext *ctx)
> {
> + int rc;
> + rc = 0;
> if (!ctx->linux_aio) {
> - ctx->linux_aio = laio_init();
> - laio_attach_aio_context(ctx->linux_aio, ctx);
> + rc = laio_init(&ctx->linux_aio);
> + if (rc == 0) {
> + laio_attach_aio_context(ctx->linux_aio, ctx);
> + }
> }
> + return rc;
> +}
> +
> +LinuxAioState *aio_get_linux_aio(AioContext *ctx)
> +{
> + assert(ctx->linux_aio);
> return ctx->linux_aio;
> }
> #endif
> --
> 2.17.1
>
Fam