Am 24.02.2018 um 00:51 hat John Snow geschrieben:
> The state transition table has mostly been implied. We're about to make
> it a bit more complex, so let's make the STM explicit instead.
>
> Perform state transitions with a function that for now just asserts the
> transition is appropriate.
>
> Transitions:
> Undefined -> Created: During job initialization.
> Created -> Running: Once the job is started.
> Jobs cannot transition from "Created" to "Paused"
> directly, but will instead synchronously transition
> to running to paused immediately.
> Running -> Paused: Normal workflow for pauses.
> Running -> Ready: Normal workflow for jobs reaching their sync point.
> (e.g. mirror)
> Ready -> Standby: Normal workflow for pausing ready jobs.
> Paused -> Running: Normal resume.
> Standby -> Ready: Resume of a Standby job.
>
>
> +---------+
> |UNDEFINED|
> +--+------+
> |
> +--v----+
> |CREATED|
> +--+----+
> |
> +--v----+ +------+
> |RUNNING<----->PAUSED|
> +--+----+ +------+
> |
> +--v--+ +-------+
> |READY<------->STANDBY|
> +-----+ +-------+
>
>
> Notably, there is no state presently defined as of this commit that
> deals with a job after the "running" or "ready" states, so this table
> will be adjusted alongside the commits that introduce those states.
>
> Signed-off-by: John Snow <js...@redhat.com>
> ---
> block/trace-events | 3 +++
> blockjob.c | 42 ++++++++++++++++++++++++++++++++++++------
> 2 files changed, 39 insertions(+), 6 deletions(-)
>
> diff --git a/block/trace-events b/block/trace-events
> index 02dd80ff0c..b75a0c8409 100644
> --- a/block/trace-events
> +++ b/block/trace-events
> @@ -4,6 +4,9 @@
> bdrv_open_common(void *bs, const char *filename, int flags, const char
> *format_name) "bs %p filename \"%s\" flags 0x%x format_name \"%s\""
> bdrv_lock_medium(void *bs, bool locked) "bs %p locked %d"
>
> +# blockjob.c
> +block_job_state_transition(void *job, int ret, const char *legal, const
> char *s0, const char *s1) "job %p (ret: %d) attempting %s transition
> (%s-->%s)"
> +
> # block/block-backend.c
> blk_co_preadv(void *blk, void *bs, int64_t offset, unsigned int bytes, int
> flags) "blk %p bs %p offset %"PRId64" bytes %u flags 0x%x"
> blk_co_pwritev(void *blk, void *bs, int64_t offset, unsigned int bytes, int
> flags) "blk %p bs %p offset %"PRId64" bytes %u flags 0x%x"
> diff --git a/blockjob.c b/blockjob.c
> index 1be9c20cff..d745b3bb69 100644
> --- a/blockjob.c
> +++ b/blockjob.c
> @@ -28,6 +28,7 @@
> #include "block/block.h"
> #include "block/blockjob_int.h"
> #include "block/block_int.h"
> +#include "block/trace.h"
> #include "sysemu/block-backend.h"
> #include "qapi/error.h"
> #include "qapi/qmp/qerror.h"
> @@ -41,6 +42,34 @@
> * block_job_enter. */
> static QemuMutex block_job_mutex;
>
> +/* BlockJob State Transition Table */
> +bool BlockJobSTT[BLOCK_JOB_STATUS__MAX][BLOCK_JOB_STATUS__MAX] = {
> + /* U, C, R, P, Y, S */
> + /* U: */ [BLOCK_JOB_STATUS_UNDEFINED] = {0, 1, 0, 0, 0, 0},
Even at the end of the series, this is the only use of
BLOCK_JOB_STATUS_UNDEFINED.
> + /* C: */ [BLOCK_JOB_STATUS_CREATED] = {0, 0, 1, 0, 0, 0},
> + /* R: */ [BLOCK_JOB_STATUS_RUNNING] = {0, 0, 0, 1, 1, 0},
> + /* P: */ [BLOCK_JOB_STATUS_PAUSED] = {0, 0, 1, 0, 0, 0},
> + /* Y: */ [BLOCK_JOB_STATUS_READY] = {0, 0, 0, 0, 0, 1},
> + /* S: */ [BLOCK_JOB_STATUS_STANDBY] = {0, 0, 0, 0, 1, 0},
> +};
> +
> +static void block_job_state_transition(BlockJob *job, BlockJobStatus s1)
> +{
> + BlockJobStatus s0 = job->status;
> + if (s0 == s1) {
> + return;
> + }
> + assert(s1 >= 0 && s1 <= BLOCK_JOB_STATUS__MAX);
> + trace_block_job_state_transition(job, job->ret, BlockJobSTT[s0][s1] ?
> + "allowed" : "disallowed",
> + qapi_enum_lookup(&BlockJobStatus_lookup,
> + s0),
> + qapi_enum_lookup(&BlockJobStatus_lookup,
> + s1));
> + assert(BlockJobSTT[s0][s1]);
> + job->status = s1;
> +}
> +
> static void block_job_lock(void)
> {
> qemu_mutex_lock(&block_job_mutex);
> @@ -320,7 +349,7 @@ void block_job_start(BlockJob *job)
> job->pause_count--;
> job->busy = true;
> job->paused = false;
> - job->status = BLOCK_JOB_STATUS_RUNNING;
> + block_job_state_transition(job, BLOCK_JOB_STATUS_RUNNING);
> bdrv_coroutine_enter(blk_bs(job->blk), job->co);
> }
>
> @@ -704,6 +733,7 @@ void *block_job_create(const char *job_id, const
> BlockJobDriver *driver,
> job->refcnt = 1;
> job->manual = (flags & BLOCK_JOB_MANUAL);
> job->status = BLOCK_JOB_STATUS_CREATED;
> + block_job_state_transition(job, BLOCK_JOB_STATUS_CREATED);
So did you intend to start with BLOCK_JOB_STATUS_UNDEFINED and then
transition to BLOCK_JOB_STATUS_CREATED?
Or should we completely remove BLOCK_JOB_STATUS_UNDEFINED, keep the
initialisation and not call block_job_state_transition() here?
Kevin
