linux-kernel - Re: [PATCH] pci/ehp_hpc: Convert timers to use timer

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Message-ID: <20171005211210.GY25517@bhelgaas-glaptop.roam.corp.google.com>
Date:   Thu, 5 Oct 2017 16:12:10 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Kees Cook <keescook@...omium.org>
Cc:     linux-kernel@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Mayurkumar Patel <mayurkumar.patel@...el.com>,
        Keith Busch <keith.busch@...el.com>, linux-pci@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] pci/ehp_hpc: Convert timers to use timer_setup()

On Wed, Oct 04, 2017 at 05:53:48PM -0700, Kees Cook wrote:
> In preparation for unconditionally passing the struct timer_list pointer to
> all timer callbacks, switch to using the new timer_setup() and from_timer()
> to pass the timer pointer explicitly. This fixes what appears to be a bug
> in passing the wrong pointer to the timer handler (address of ctrl pointer
> instead of ctrl pointer).
> 
> Cc: Bjorn Helgaas <bhelgaas@...gle.com>
> Cc: Mika Westerberg <mika.westerberg@...ux.intel.com>
> Cc: Mayurkumar Patel <mayurkumar.patel@...el.com>
> Cc: Keith Busch <keith.busch@...el.com>
> Cc: linux-pci@...r.kernel.org
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Signed-off-by: Kees Cook <keescook@...omium.org>

Applied to pci/hotplug for v4.15, thanks!

> ---
> This requires commit 686fef928bba ("timer: Prepare to change timer
> callback argument type") in v4.14-rc3, but should be otherwise
> stand-alone.
> ---
>  drivers/pci/hotplug/pciehp_hpc.c | 12 ++++--------
>  1 file changed, 4 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
> index e5d5ce9e3010..ba5055c5115c 100644
> --- a/drivers/pci/hotplug/pciehp_hpc.c
> +++ b/drivers/pci/hotplug/pciehp_hpc.c
> @@ -50,14 +50,13 @@ static irqreturn_t pcie_isr(int irq, void *dev_id);
>  static void start_int_poll_timer(struct controller *ctrl, int sec);
>  
>  /* This is the interrupt polling timeout function. */
> -static void int_poll_timeout(unsigned long data)
> +static void int_poll_timeout(struct timer_list *t)
>  {
> -	struct controller *ctrl = (struct controller *)data;
> +	struct controller *ctrl = from_timer(ctrl, t, poll_timer);
>  
>  	/* Poll for interrupt events.  regs == NULL => polling */
>  	pcie_isr(0, ctrl);
>  
> -	init_timer(&ctrl->poll_timer);
>  	if (!pciehp_poll_time)
>  		pciehp_poll_time = 2; /* default polling interval is 2 sec */
>  
> @@ -71,8 +70,6 @@ static void start_int_poll_timer(struct controller *ctrl, int sec)
>  	if ((sec <= 0) || (sec > 60))
>  		sec = 2;
>  
> -	ctrl->poll_timer.function = &int_poll_timeout;
> -	ctrl->poll_timer.data = (unsigned long)ctrl;
>  	ctrl->poll_timer.expires = jiffies + sec * HZ;
>  	add_timer(&ctrl->poll_timer);
>  }
> @@ -83,7 +80,7 @@ static inline int pciehp_request_irq(struct controller *ctrl)
>  
>  	/* Install interrupt polling timer. Start with 10 sec delay */
>  	if (pciehp_poll_mode) {
> -		init_timer(&ctrl->poll_timer);
> +		timer_setup(&ctrl->poll_timer, int_poll_timeout, 0);
>  		start_int_poll_timer(ctrl, 10);
>  		return 0;
>  	}
> @@ -764,8 +761,7 @@ int pciehp_reset_slot(struct slot *slot, int probe)
>  	ctrl_dbg(ctrl, "%s: SLOTCTRL %x write cmd %x\n", __func__,
>  		 pci_pcie_cap(ctrl->pcie->port) + PCI_EXP_SLTCTL, ctrl_mask);
>  	if (pciehp_poll_mode)
> -		int_poll_timeout(ctrl->poll_timer.data);
> -
> +		int_poll_timeout(&ctrl->poll_timer);
>  	return 0;
>  }
>  
> -- 
> 2.7.4
> 
> 
> -- 
> Kees Cook
> Pixel Security