[v2,2/9] powerpc/eeh: Manage EEH_PE_RECOVERING inside eeh_handle_normal_event()

Currently the EEH_PE_RECOVERING flag for a PE is managed by both the
caller and callee of eeh_handle_normal_event() (among other places not
considered here). This is complicated by the fact that the PE may
or may not have been invalidated by the call.

So move the callee's handling into eeh_handle_normal_event(), which
clarifies it and allows the return type to be changed to void (because
it no longer needs to indicate at the PE has been invalidated).

This should not change behaviour except in eeh_event_handler() where
it was previously possible to cause eeh_pe_state_clear() to be called
on an invalid PE, which is now avoided.

Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
---
 arch/powerpc/include/asm/eeh_event.h |  2 +-
 arch/powerpc/kernel/eeh_driver.c     | 29 +++++++++++------------------
 arch/powerpc/kernel/eeh_event.c      |  2 --
 3 files changed, 12 insertions(+), 21 deletions(-)

On 19/3/18 1:46 pm, Sam Bobroff wrote:
> Currently the EEH_PE_RECOVERING flag for a PE is managed by both the
> caller and callee of eeh_handle_normal_event() (among other places not
> considered here). This is complicated by the fact that the PE may
> or may not have been invalidated by the call.
> 
> So move the callee's handling into eeh_handle_normal_event(), which
> clarifies it and allows the return type to be changed to void (because
> it no longer needs to indicate at the PE has been invalidated).
> 
> This should not change behaviour except in eeh_event_handler() where
> it was previously possible to cause eeh_pe_state_clear() to be called
> on an invalid PE, which is now avoided.
> 
> Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>

Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>


> ---
>  arch/powerpc/include/asm/eeh_event.h |  2 +-
>  arch/powerpc/kernel/eeh_driver.c     | 29 +++++++++++------------------
>  arch/powerpc/kernel/eeh_event.c      |  2 --
>  3 files changed, 12 insertions(+), 21 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/eeh_event.h b/arch/powerpc/include/asm/eeh_event.h
> index 0a168038882d..9884e872686f 100644
> --- a/arch/powerpc/include/asm/eeh_event.h
> +++ b/arch/powerpc/include/asm/eeh_event.h
> @@ -34,7 +34,7 @@ struct eeh_event {
>  int eeh_event_init(void);
>  int eeh_send_failure_event(struct eeh_pe *pe);
>  void eeh_remove_event(struct eeh_pe *pe, bool force);
> -bool eeh_handle_normal_event(struct eeh_pe *pe);
> +void eeh_handle_normal_event(struct eeh_pe *pe);
>  void eeh_handle_special_event(void);
>  
>  #endif /* __KERNEL__ */
> diff --git a/arch/powerpc/kernel/eeh_driver.c b/arch/powerpc/kernel/eeh_driver.c
> index 51b21c97910f..5b7a5ed4db4d 100644
> --- a/arch/powerpc/kernel/eeh_driver.c
> +++ b/arch/powerpc/kernel/eeh_driver.c
> @@ -733,7 +733,8 @@ static int eeh_reset_device(struct eeh_pe *pe, struct pci_bus *bus,
>  
>  /**
>   * eeh_handle_normal_event - Handle EEH events on a specific PE
> - * @pe: EEH PE
> + * @pe: EEH PE - which should not be used after we return, as it may
> + * have been invalidated.
>   *
>   * Attempts to recover the given PE.  If recovery fails or the PE has failed
>   * too many times, remove the PE.
> @@ -750,10 +751,8 @@ static int eeh_reset_device(struct eeh_pe *pe, struct pci_bus *bus,
>   * & devices under this slot, and then finally restarting the device
>   * drivers (which cause a second set of hotplug events to go out to
>   * userspace).
> - *
> - * Returns true if @pe should no longer be used, else false.
>   */
> -bool eeh_handle_normal_event(struct eeh_pe *pe)
> +void eeh_handle_normal_event(struct eeh_pe *pe)
>  {
>  	struct pci_bus *frozen_bus;
>  	struct eeh_dev *edev, *tmp;
> @@ -765,9 +764,11 @@ bool eeh_handle_normal_event(struct eeh_pe *pe)
>  	if (!frozen_bus) {
>  		pr_err("%s: Cannot find PCI bus for PHB#%x-PE#%x\n",
>  			__func__, pe->phb->global_number, pe->addr);
> -		return false;
> +		return;
>  	}
>  
> +	eeh_pe_state_mark(pe, EEH_PE_RECOVERING);
> +
>  	eeh_pe_update_time_stamp(pe);
>  	pe->freeze_count++;
>  	if (pe->freeze_count > eeh_max_freezes) {
> @@ -904,7 +905,7 @@ bool eeh_handle_normal_event(struct eeh_pe *pe)
>  	pr_info("EEH: Notify device driver to resume\n");
>  	eeh_pe_dev_traverse(pe, eeh_report_resume, NULL);
>  
> -	return false;
> +	goto final;
>  
>  hard_fail:
>  	/*
> @@ -940,12 +941,12 @@ bool eeh_handle_normal_event(struct eeh_pe *pe)
>  			pci_lock_rescan_remove();
>  			pci_hp_remove_devices(frozen_bus);
>  			pci_unlock_rescan_remove();
> -
>  			/* The passed PE should no longer be used */
> -			return true;
> +			return;
>  		}
>  	}
> -	return false;
> +final:
> +	eeh_pe_state_clear(pe, EEH_PE_RECOVERING);
>  }
>  
>  /**
> @@ -1018,15 +1019,7 @@ void eeh_handle_special_event(void)
>  		 */
>  		if (rc == EEH_NEXT_ERR_FROZEN_PE ||
>  		    rc == EEH_NEXT_ERR_FENCED_PHB) {
> -			/*
> -			 * eeh_handle_normal_event() can make the PE stale if it
> -			 * determines that the PE cannot possibly be recovered.
> -			 * Don't modify the PE state if that's the case.
> -			 */
> -			if (eeh_handle_normal_event(pe))
> -				continue;
> -
> -			eeh_pe_state_clear(pe, EEH_PE_RECOVERING);
> +			eeh_handle_normal_event(pe);
>  		} else {
>  			pci_lock_rescan_remove();
>  			list_for_each_entry(hose, &hose_list, list_node) {
> diff --git a/arch/powerpc/kernel/eeh_event.c b/arch/powerpc/kernel/eeh_event.c
> index 872bcfe8f90e..61c9356bf9c9 100644
> --- a/arch/powerpc/kernel/eeh_event.c
> +++ b/arch/powerpc/kernel/eeh_event.c
> @@ -73,7 +73,6 @@ static int eeh_event_handler(void * dummy)
>  		/* We might have event without binding PE */
>  		pe = event->pe;
>  		if (pe) {
> -			eeh_pe_state_mark(pe, EEH_PE_RECOVERING);
>  			if (pe->type & EEH_PE_PHB)
>  				pr_info("EEH: Detected error on PHB#%x\n",
>  					 pe->phb->global_number);
> @@ -82,7 +81,6 @@ static int eeh_event_handler(void * dummy)
>  					"PHB#%x-PE#%x\n",
>  					pe->phb->global_number, pe->addr);
>  			eeh_handle_normal_event(pe);
> -			eeh_pe_state_clear(pe, EEH_PE_RECOVERING);
>  		} else {
>  			eeh_handle_special_event();
>  		}
>