diff mbox series

[12/42] job: Maintain a list of all jobs

Message ID 20180509162637.15575-13-kwolf@redhat.com
State New
Headers show
Series Generic background jobs | expand

Commit Message

Kevin Wolf May 9, 2018, 4:26 p.m. UTC
This moves the job list from BlockJob to Job. Now we can check for
duplicate IDs in job_create().

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/block/blockjob.h |  3 ---
 include/qemu/job.h       | 19 +++++++++++++++++++
 blockjob.c               | 47 +++++++++++++++++++++++++----------------------
 job.c                    | 31 +++++++++++++++++++++++++++++++
 4 files changed, 75 insertions(+), 25 deletions(-)

Comments

Max Reitz May 14, 2018, 1:59 p.m. UTC | #1
On 2018-05-09 18:26, Kevin Wolf wrote:
> This moves the job list from BlockJob to Job. Now we can check for
> duplicate IDs in job_create().
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  include/block/blockjob.h |  3 ---
>  include/qemu/job.h       | 19 +++++++++++++++++++
>  blockjob.c               | 47 +++++++++++++++++++++++++----------------------
>  job.c                    | 31 +++++++++++++++++++++++++++++++
>  4 files changed, 75 insertions(+), 25 deletions(-)

Reviewed-by: Max Reitz <mreitz@redhat.com>
John Snow May 14, 2018, 8:42 p.m. UTC | #2
On 05/09/2018 12:26 PM, Kevin Wolf wrote:
> This moves the job list from BlockJob to Job. Now we can check for
> duplicate IDs in job_create().
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>

Reviewed-by: John Snow <jsnow@redhat.com>
Eric Blake May 16, 2018, 6:03 p.m. UTC | #3
On 05/09/2018 11:26 AM, Kevin Wolf wrote:
> This moves the job list from BlockJob to Job. Now we can check for
> duplicate IDs in job_create().
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>   include/block/blockjob.h |  3 ---
>   include/qemu/job.h       | 19 +++++++++++++++++++
>   blockjob.c               | 47 +++++++++++++++++++++++++----------------------
>   job.c                    | 31 +++++++++++++++++++++++++++++++
>   4 files changed, 75 insertions(+), 25 deletions(-)

> @@ -71,4 +75,19 @@ JobType job_type(Job *job);
>   /** Returns the enum string for the JobType of a given Job. */
>   const char *job_type_str(Job *job);
>   
> +/**
> + * Get the next element from the list of block jobs after @job, or the
> + * first one if @job is %NULL.
> + *
> + * Returns the requested job, or %NULL if there are no more jobs left.
> + */
> +Job *job_next(Job *job);

The new code is supposed to allow you to prime the search by passing in 
NULL.  This looks similar to the semantics originally held by 
block_job_next(), where


> -BlockJob *block_job_next(BlockJob *job)
> +static bool is_block_job(Job *job)
>   {
> -    if (!job) {
> -        return QLIST_FIRST(&block_jobs);
> -    }

the old code did so by special-casing an incoming NULL.

> -    return QLIST_NEXT(job, job_list);
> +    return job_type(job) == JOB_TYPE_BACKUP ||
> +           job_type(job) == JOB_TYPE_COMMIT ||
> +           job_type(job) == JOB_TYPE_MIRROR ||
> +           job_type(job) == JOB_TYPE_STREAM;
> +}
> +
> +BlockJob *block_job_next(BlockJob *bjob)
> +{
> +    Job *job = &bjob->job;

But the new code blindly dereferences what may be a NULL bjob.  Taking 
the address of a member of the NULL pointer may happen to work if that 
member is at offset 0, but is also likely to trigger compiler or 
sanitizer warnings; and does not work if the member is not at offset 0.

I think all you have to do is:

Job *job = bjob ? &bjob->job : NULL;

> +
> +    do {
> +        job = job_next(job);
> +    } while (job && !is_block_job(job));
> +
> +
> +    return job ? container_of(job, BlockJob, job) : NULL;

Why two blank lines?
diff mbox series

Patch

diff --git a/include/block/blockjob.h b/include/block/blockjob.h
index 8acc1a236a..8946f118f3 100644
--- a/include/block/blockjob.h
+++ b/include/block/blockjob.h
@@ -105,9 +105,6 @@  typedef struct BlockJob {
      */
     bool deferred_to_main_loop;
 
-    /** Element of the list of block jobs */
-    QLIST_ENTRY(BlockJob) job_list;
-
     /** Status that is published by the query-block-jobs QMP API */
     BlockDeviceIoStatus iostatus;
 
diff --git a/include/qemu/job.h b/include/qemu/job.h
index ee1f5d1ef4..6555ab4c36 100644
--- a/include/qemu/job.h
+++ b/include/qemu/job.h
@@ -27,6 +27,7 @@ 
 #define JOB_H
 
 #include "qapi/qapi-types-block-core.h"
+#include "qemu/queue.h"
 
 typedef struct JobDriver JobDriver;
 
@@ -39,6 +40,9 @@  typedef struct Job {
 
     /** The type of this job. */
     const JobDriver *driver;
+
+    /** Element of the list of jobs */
+    QLIST_ENTRY(Job) job_list;
 } Job;
 
 /**
@@ -71,4 +75,19 @@  JobType job_type(Job *job);
 /** Returns the enum string for the JobType of a given Job. */
 const char *job_type_str(Job *job);
 
+/**
+ * Get the next element from the list of block jobs after @job, or the
+ * first one if @job is %NULL.
+ *
+ * Returns the requested job, or %NULL if there are no more jobs left.
+ */
+Job *job_next(Job *job);
+
+/**
+ * Get the job identified by @id (which must not be %NULL).
+ *
+ * Returns the requested job, or %NULL if it doesn't exist.
+ */
+Job *job_get(const char *id);
+
 #endif
diff --git a/blockjob.c b/blockjob.c
index f1bff2272e..29747dfdc0 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -129,8 +129,6 @@  struct BlockJobTxn {
     int refcnt;
 };
 
-static QLIST_HEAD(, BlockJob) block_jobs = QLIST_HEAD_INITIALIZER(block_jobs);
-
 /*
  * The block job API is composed of two categories of functions.
  *
@@ -146,25 +144,35 @@  static QLIST_HEAD(, BlockJob) block_jobs = QLIST_HEAD_INITIALIZER(block_jobs);
  * blockjob_int.h.
  */
 
-BlockJob *block_job_next(BlockJob *job)
+static bool is_block_job(Job *job)
 {
-    if (!job) {
-        return QLIST_FIRST(&block_jobs);
-    }
-    return QLIST_NEXT(job, job_list);
+    return job_type(job) == JOB_TYPE_BACKUP ||
+           job_type(job) == JOB_TYPE_COMMIT ||
+           job_type(job) == JOB_TYPE_MIRROR ||
+           job_type(job) == JOB_TYPE_STREAM;
+}
+
+BlockJob *block_job_next(BlockJob *bjob)
+{
+    Job *job = &bjob->job;
+
+    do {
+        job = job_next(job);
+    } while (job && !is_block_job(job));
+
+
+    return job ? container_of(job, BlockJob, job) : NULL;
 }
 
 BlockJob *block_job_get(const char *id)
 {
-    BlockJob *job;
+    Job *job = job_get(id);
 
-    QLIST_FOREACH(job, &block_jobs, job_list) {
-        if (job->job.id && !strcmp(id, job->job.id)) {
-            return job;
-        }
+    if (job && is_block_job(job)) {
+        return container_of(job, BlockJob, job);
+    } else {
+        return NULL;
     }
-
-    return NULL;
 }
 
 BlockJobTxn *block_job_txn_new(void)
@@ -239,7 +247,6 @@  void block_job_unref(BlockJob *job)
         assert(job->status == BLOCK_JOB_STATUS_NULL);
         assert(!job->txn);
         BlockDriverState *bs = blk_bs(job->blk);
-        QLIST_REMOVE(job, job_list);
         bs->job = NULL;
         block_job_remove_all_bdrv(job);
         blk_remove_aio_context_notifier(job->blk,
@@ -804,7 +811,7 @@  void block_job_cancel_sync_all(void)
     BlockJob *job;
     AioContext *aio_context;
 
-    while ((job = QLIST_FIRST(&block_jobs))) {
+    while ((job = block_job_next(NULL))) {
         aio_context = blk_get_aio_context(job->blk);
         aio_context_acquire(aio_context);
         block_job_cancel_sync(job);
@@ -934,10 +941,6 @@  void *block_job_create(const char *job_id, const BlockJobDriver *driver,
             error_setg(errp, "Cannot specify job ID for internal block job");
             return NULL;
         }
-        if (block_job_get(job_id)) {
-            error_setg(errp, "Job ID '%s' already in use", job_id);
-            return NULL;
-        }
     }
 
     blk = blk_new(perm, shared_perm);
@@ -953,6 +956,8 @@  void *block_job_create(const char *job_id, const BlockJobDriver *driver,
         return NULL;
     }
 
+    assert(is_block_job(&job->job));
+
     job->driver        = driver;
     job->blk           = blk;
     job->cb            = cb;
@@ -975,8 +980,6 @@  void *block_job_create(const char *job_id, const BlockJobDriver *driver,
 
     bdrv_op_unblock(bs, BLOCK_OP_TYPE_DATAPLANE, job->blocker);
 
-    QLIST_INSERT_HEAD(&block_jobs, job, job_list);
-
     blk_add_aio_context_notifier(blk, block_job_attached_aio_context,
                                  block_job_detach_aio_context, job);
 
diff --git a/job.c b/job.c
index a36425498d..00f7968c50 100644
--- a/job.c
+++ b/job.c
@@ -29,6 +29,8 @@ 
 #include "qemu/job.h"
 #include "qemu/id.h"
 
+static QLIST_HEAD(, Job) jobs = QLIST_HEAD_INITIALIZER(jobs);
+
 JobType job_type(Job *job)
 {
     return job->driver->job_type;
@@ -39,6 +41,27 @@  const char *job_type_str(Job *job)
     return JobType_str(job_type(job));
 }
 
+Job *job_next(Job *job)
+{
+    if (!job) {
+        return QLIST_FIRST(&jobs);
+    }
+    return QLIST_NEXT(job, job_list);
+}
+
+Job *job_get(const char *id)
+{
+    Job *job;
+
+    QLIST_FOREACH(job, &jobs, job_list) {
+        if (job->id && !strcmp(id, job->id)) {
+            return job;
+        }
+    }
+
+    return NULL;
+}
+
 void *job_create(const char *job_id, const JobDriver *driver, Error **errp)
 {
     Job *job;
@@ -48,17 +71,25 @@  void *job_create(const char *job_id, const JobDriver *driver, Error **errp)
             error_setg(errp, "Invalid job ID '%s'", job_id);
             return NULL;
         }
+        if (job_get(job_id)) {
+            error_setg(errp, "Job ID '%s' already in use", job_id);
+            return NULL;
+        }
     }
 
     job = g_malloc0(driver->instance_size);
     job->driver        = driver;
     job->id            = g_strdup(job_id);
 
+    QLIST_INSERT_HEAD(&jobs, job, job_list);
+
     return job;
 }
 
 void job_delete(Job *job)
 {
+    QLIST_REMOVE(job, job_list);
+
     g_free(job->id);
     g_free(job);
 }