WorkStruct: Pass the work_struct pointer instead of context data

Pass the work_struct pointer to the work function rather than context data.
The work function can use container_of() to work out the data.

For the cases where the container of the work_struct may go away the moment the
pending bit is cleared, it is made possible to defer the release of the
structure by deferring the clearing of the pending bit.

To make this work, an extra flag is introduced into the management side of the
work_struct.  This governs auto-release of the structure upon execution.

Ordinarily, the work queue executor would release the work_struct for further
scheduling or deallocation by clearing the pending bit prior to jumping to the
work function.  This means that, unless the driver makes some guarantee itself
that the work_struct won't go away, the work function may not access anything
else in the work_struct or its container lest they be deallocated..  This is a
problem if the auxiliary data is taken away (as done by the last patch).

However, if the pending bit is *not* cleared before jumping to the work
function, then the work function *may* access the work_struct and its container
with no problems.  But then the work function must itself release the
work_struct by calling work_release().

In most cases, automatic release is fine, so this is the default.  Special
initiators exist for the non-auto-release case (ending in _NAR).


Signed-Off-By: David Howells <dhowells@redhat.com>

3 files changed, 6 insertions, 6 deletions

diff --git a/drivers/pci/pcie/aer/aerdrv.c b/drivers/pci/pcie/aer/aerdrv.c
index 04c43ef..55866b6 100644
--- a/drivers/pci/pcie/aer/aerdrv.c
+++ b/drivers/pci/pcie/aer/aerdrv.c
@@ -160,7 +160,7 @@ static struct aer_rpc* aer_alloc_rpc(struct pcie_device *dev)
 	rpc->e_lock = SPIN_LOCK_UNLOCKED;
 
 	rpc->rpd = dev;
-	INIT_WORK(&rpc->dpc_handler, aer_isr, (void *)dev);
+	INIT_WORK(&rpc->dpc_handler, aer_isr);
 	rpc->prod_idx = rpc->cons_idx = 0;
 	mutex_init(&rpc->rpc_mutex);
 	init_waitqueue_head(&rpc->wait_release);
diff --git a/drivers/pci/pcie/aer/aerdrv.h b/drivers/pci/pcie/aer/aerdrv.h
index daf0cad..3c0a58f 100644
--- a/drivers/pci/pcie/aer/aerdrv.h
+++ b/drivers/pci/pcie/aer/aerdrv.h
@@ -118,7 +118,7 @@ extern struct bus_type pcie_port_bus_type;
 extern void aer_enable_rootport(struct aer_rpc *rpc);
 extern void aer_delete_rootport(struct aer_rpc *rpc);
 extern int aer_init(struct pcie_device *dev);
-extern void aer_isr(void *context);
+extern void aer_isr(struct work_struct *work);
 extern void aer_print_error(struct pci_dev *dev, struct aer_err_info *info);
 extern int aer_osc_setup(struct pci_dev *dev);
 
diff --git a/drivers/pci/pcie/aer/aerdrv_core.c b/drivers/pci/pcie/aer/aerdrv_core.c
index 1c7e660..08e1303 100644
--- a/drivers/pci/pcie/aer/aerdrv_core.c
+++ b/drivers/pci/pcie/aer/aerdrv_core.c
@@ -690,14 +690,14 @@ static void aer_isr_one_error(struct pcie_device *p_device,
 
 /**
  * aer_isr - consume errors detected by root port
- * @context: pointer to a private data of pcie device
+ * @work: definition of this work item
  *
  * Invoked, as DPC, when root port records new detected error
  **/
-void aer_isr(void *context)
+void aer_isr(struct work_struct *work)
 {
-	struct pcie_device *p_device = (struct pcie_device *) context;
-	struct aer_rpc *rpc = get_service_data(p_device);
+	struct aer_rpc *rpc = container_of(work, struct aer_rpc, dpc_handler);
+	struct pcie_device *p_device = rpc->rpd;
 	struct aer_err_source *e_src;
 
 	mutex_lock(&rpc->rpc_mutex);