From c9de40505f257a325e76f630c203432c77795461 Mon Sep 17 00:00:00 2001 From: John Snow Date: Sat, 10 Mar 2018 03:27:30 -0500 Subject: [PATCH] blockjobs: add state transition table 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 Signed-off-by: Kevin Wolf --- block/trace-events | 3 +++ blockjob.c | 40 +++++++++++++++++++++++++++++++++------- 2 files changed, 36 insertions(+), 7 deletions(-) diff --git a/block/trace-events b/block/trace-events index 7493d521dc..112a8972bb 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 719169cccd..442426e27b 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/qapi-events-block-core.h" @@ -41,6 +42,31 @@ * 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}, + /* 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; + 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 +346,7 @@ 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); } @@ -702,7 +728,7 @@ void *block_job_create(const char *job_id, const BlockJobDriver *driver, job->paused = true; job->pause_count = 1; job->refcnt = 1; - job->status = BLOCK_JOB_STATUS_CREATED; + block_job_state_transition(job, BLOCK_JOB_STATUS_CREATED); aio_timer_init(qemu_get_aio_context(), &job->sleep_timer, QEMU_CLOCK_REALTIME, SCALE_NS, block_job_sleep_timer_cb, job); @@ -817,13 +843,13 @@ void coroutine_fn block_job_pause_point(BlockJob *job) if (block_job_should_pause(job) && !block_job_is_cancelled(job)) { BlockJobStatus status = job->status; - job->status = status == BLOCK_JOB_STATUS_READY ? \ - BLOCK_JOB_STATUS_STANDBY : \ - BLOCK_JOB_STATUS_PAUSED; + block_job_state_transition(job, status == BLOCK_JOB_STATUS_READY ? \ + BLOCK_JOB_STATUS_STANDBY : \ + BLOCK_JOB_STATUS_PAUSED); job->paused = true; block_job_do_yield(job, -1); job->paused = false; - job->status = status; + block_job_state_transition(job, status); } if (job->driver->resume) { @@ -929,7 +955,7 @@ void block_job_iostatus_reset(BlockJob *job) void block_job_event_ready(BlockJob *job) { - job->status = BLOCK_JOB_STATUS_READY; + block_job_state_transition(job, BLOCK_JOB_STATUS_READY); job->ready = true; if (block_job_is_internal(job)) {