Re: [PATCH 7/7] powerpc/eeh: Add eeh_force_recover to debugfs

[Sam Bobroff <sbobroff@linux.ibm.com>]

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On Fri, Feb 08, 2019 at 02:08:02PM +1100, Oliver O'Halloran wrote:
> This patch adds a debugfs interface to force scheduling a recovery event.
> This can be used to recover a specific PE or schedule a "special" recovery
> even that checks for errors at the PHB level.
> To force a recovery of a normal PE, use:
> 
>  echo '<#pe>:<#phb>' > /sys/kernel/debug/powerpc/eeh_force_recover

How about placing these in the per-PHB debugfs directory?
echo '<#pe>' > /sys/kernel/debug/powerpc/PCI0000/eeh_force_recover

> To force a scan broken PHBs:
> 
>  echo 'null' > /sys/kernel/debug/powerpc/eeh_force_recover

And keep this one where it is, and just trigger with any write (or a '1'
or whatever)?

Sam.

> Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
> ---
>  arch/powerpc/include/asm/eeh_event.h |  1 +
>  arch/powerpc/kernel/eeh.c            | 60 ++++++++++++++++++++++++++++
>  arch/powerpc/kernel/eeh_event.c      | 25 +++++++-----
>  3 files changed, 76 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/eeh_event.h b/arch/powerpc/include/asm/eeh_event.h
> index 9884e872686f..6d0412b846ac 100644
> --- a/arch/powerpc/include/asm/eeh_event.h
> +++ b/arch/powerpc/include/asm/eeh_event.h
> @@ -33,6 +33,7 @@ struct eeh_event {
>  
>  int eeh_event_init(void);
>  int eeh_send_failure_event(struct eeh_pe *pe);
> +int __eeh_send_failure_event(struct eeh_pe *pe);
>  void eeh_remove_event(struct eeh_pe *pe, bool force);
>  void eeh_handle_normal_event(struct eeh_pe *pe);
>  void eeh_handle_special_event(void);
> diff --git a/arch/powerpc/kernel/eeh.c b/arch/powerpc/kernel/eeh.c
> index 92809b137e39..63b91a4918c9 100644
> --- a/arch/powerpc/kernel/eeh.c
> +++ b/arch/powerpc/kernel/eeh.c
> @@ -1805,6 +1805,63 @@ static int eeh_enable_dbgfs_get(void *data, u64 *val)
>  
>  DEFINE_DEBUGFS_ATTRIBUTE(eeh_enable_dbgfs_ops, eeh_enable_dbgfs_get,
>  			 eeh_enable_dbgfs_set, "0x%llx\n");
> +
> +static ssize_t eeh_force_recover_write(struct file *filp,
> +				const char __user *user_buf,
> +				size_t count, loff_t *ppos)
> +{
> +	struct pci_controller *hose;
> +	uint32_t phbid, pe_no;
> +	struct eeh_pe *pe;
> +	char buf[20];
> +	int ret;
> +
> +	ret = simple_write_to_buffer(buf, sizeof(buf), ppos, user_buf, count);
> +	if (!ret)
> +		return -EFAULT;
> +
> +	/*
> +	 * When PE is NULL the event is a "special" event. Rather than
> +	 * recovering a specific PE it forces the EEH core to scan for failed
> +	 * PHBs and recovers each. This needs to be done before any device
> +	 * recoveries can occur.
> +	 */
> +	if (!strncmp(buf, "null", 4)) {
> +		pr_err("sending failure event\n");
> +		__eeh_send_failure_event(NULL);
> +		return count;
> +	}
> +
> +	ret = sscanf(buf, "%x:%x", &phbid, &pe_no);
> +	if (ret != 2)
> +		return -EINVAL;
> +
> +	hose = pci_find_hose_for_domain(phbid);
> +	if (!hose)
> +		return -ENODEV;
> +
> +	/* Retrieve PE */
> +	pe = eeh_pe_get(hose, pe_no, 0);
> +	if (!pe)
> +		return -ENODEV;
> +
> +	/*
> +	 * We don't do any state checking here since the detection
> +	 * process is async to the recovery process. The recovery
> +	 * thread *should* not break even if we schedule a recovery
> +	 * from an odd state (e.g. PE removed, or recovery of a
> +	 * non-isolated PE)
> +	 */
> +	__eeh_send_failure_event(pe);
> +
> +	return ret < 0 ? ret : count;
> +}
> +
> +static const struct file_operations eeh_force_recover_fops = {
> +	.open	= simple_open,
> +	.llseek	= no_llseek,
> +	.write	= eeh_force_recover_write,
> +};
>  #endif
>  
>  static int __init eeh_init_proc(void)
> @@ -1820,6 +1877,9 @@ static int __init eeh_init_proc(void)
>  		debugfs_create_bool("eeh_disable_recovery", 0600,
>  				powerpc_debugfs_root,
>  				&eeh_debugfs_no_recover);
> +		debugfs_create_file_unsafe("eeh_force_recover", 0600,
> +				powerpc_debugfs_root, NULL,
> +				&eeh_force_recover_fops);
>  		eeh_cache_debugfs_init();
>  #endif
>  	}
> diff --git a/arch/powerpc/kernel/eeh_event.c b/arch/powerpc/kernel/eeh_event.c
> index 19837798bb1d..539aca055d70 100644
> --- a/arch/powerpc/kernel/eeh_event.c
> +++ b/arch/powerpc/kernel/eeh_event.c
> @@ -121,20 +121,11 @@ int eeh_event_init(void)
>   * the actual event will be delivered in a normal context
>   * (from a workqueue).
>   */
> -int eeh_send_failure_event(struct eeh_pe *pe)
> +int __eeh_send_failure_event(struct eeh_pe *pe)
>  {
>  	unsigned long flags;
>  	struct eeh_event *event;
>  
> -	/*
> -	 * If we've manually supressed recovery events via debugfs
> -	 * then just drop it on the floor.
> -	 */
> -	if (eeh_debugfs_no_recover) {
> -		pr_err("EEH: Event dropped due to no_recover setting\n");
> -		return 0;
> -	}
> -
>  	event = kzalloc(sizeof(*event), GFP_ATOMIC);
>  	if (!event) {
>  		pr_err("EEH: out of memory, event not handled\n");
> @@ -153,6 +144,20 @@ int eeh_send_failure_event(struct eeh_pe *pe)
>  	return 0;
>  }
>  
> +int eeh_send_failure_event(struct eeh_pe *pe)
> +{
> +	/*
> +	 * If we've manually supressed recovery events via debugfs
> +	 * then just drop it on the floor.
> +	 */
> +	if (eeh_debugfs_no_recover) {
> +		pr_err("EEH: Event dropped due to no_recover setting\n");
> +		return 0;
> +	}
> +
> +	return __eeh_send_failure_event(pe);
> +}
> +
>  /**
>   * eeh_remove_event - Remove EEH event from the queue
>   * @pe: Event binding to the PE
> -- 
> 2.20.1
> 

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