linux-kernel - Re: [PATCH v2 7/9] PCI: hotplug: Prefer CONFIG_DYNAMIC

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Date:   Fri, 3 May 2019 15:48:52 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Frederick Lawler <fred@...dlawl.com>
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        mika.westerberg@...ux.intel.com, lukas@...ner.de,
        andriy.shevchenko@...ux.intel.com, keith.busch@...el.com,
        mr.nuke.me@...il.com, liudongdong3@...wei.com, thesven73@...il.com
Subject: Re: [PATCH v2 7/9] PCI: hotplug: Prefer CONFIG_DYNAMIC_DEBUG/DEBUG
 for dmesg logs

On Thu, May 02, 2019 at 10:59:44PM -0500, Frederick Lawler wrote:
> dbg() and ctrl_dbg() requires pciehp_debug module parameter to be set
> for debug log purposes. There are niche situations in pciehp_hpc.c where
> pciehp_debug is used: dbg_ctrl(), and pci_bus_check_dev().
> 
> Enabling CONFIG_DYNAMIC_DEBUG/DEBUG is well known for logging debug
> information. Therefore, prefer pr/pci_dbg() for debug information, and
> reserve pciehp_debug for niche situations.

I guess by "niche situations", you mean the tests in
pci_bus_check_dev() and dbg_ctrl()?

I think pci_bus_check_dev() could skip the test and just use pr_dbg().
For dbg_ctrl(), we could just remove the test (and maybe reformat
those strings so they match other messages).  That's a one-time thing
so I don't think two extra config reads that we might not print are a
problem.

I'd probably reorder these so you have five patches (or maybe more if
I missed something):

  - remove pciehp_debug uses from pci_bus_check_dev() and dbg_ctrl()
  - convert pciehp_debug to dyndbg
  - convert "dev_*(&ctrl->pcie->device)" to "pci_*(ctrl->pcie->port)"
  - add "Slot(%s)" to wrappers (could this be done with dev_fmt?)
  - remove unused wrappers

> Signed-off-by: Frederick Lawler <fred@...dlawl.com>
> ---
>  drivers/pci/hotplug/pciehp.h | 11 ++---------
>  1 file changed, 2 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/pci/hotplug/pciehp.h b/drivers/pci/hotplug/pciehp.h
> index 78325c8d961e..e852aa478802 100644
> --- a/drivers/pci/hotplug/pciehp.h
> +++ b/drivers/pci/hotplug/pciehp.h
> @@ -32,10 +32,7 @@ extern int pciehp_poll_time;
>  extern bool pciehp_debug;
>  
>  #define dbg(format, arg...)						\
> -do {									\
> -	if (pciehp_debug)						\
> -		pr_info(format, ## arg);				\
> -} while (0)
> +	pr_debug(format, ## arg);
>  #define err(format, arg...)						\
>  	pr_err(format, ## arg)
>  #define info(format, arg...)						\
> @@ -44,11 +41,7 @@ do {									\
>  	pr_warn(format, ## arg)
>  
>  #define ctrl_dbg(ctrl, format, arg...)					\
> -	do {								\
> -		if (pciehp_debug)					\
> -			pci_info(ctrl->pcie->port,			\
> -				 format, ## arg);			\
> -	} while (0)
> +	pci_dbg(ctrl->pcie->port, format, ## arg)
>  #define ctrl_err(ctrl, format, arg...)					\
>  	pci_err(ctrl->pcie->port, format, ## arg)
>  #define ctrl_info(ctrl, format, arg...)					\
> -- 
> 2.17.1
>