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Message-ID: <CAErSpo4n0souqCfnjwvA37321Wmr1RHZCX2tqx2Oa-jS_s7QYQ@mail.gmail.com>
Date: Tue, 11 Feb 2014 15:34:34 -0700
From: Bjorn Helgaas <bhelgaas@...gle.com>
To: Rajat Jain <rajatxjain@...il.com>
Cc: Rajat Jain <rajatjain@...iper.net>,
"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>,
Alex Williamson <alex.williamson@...hat.com>,
Yijing Wang <wangyijing@...wei.com>,
"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Yinghai Lu <yhlu.kernel@...il.com>,
Guenter Roeck <groeck@...iper.net>
Subject: Re: [PATCH v5 8/8] Allow Link state changes for Hot-Plug
On Mon, Feb 10, 2014 at 7:22 PM, Rajat Jain <rajatxjain@...il.com> wrote:
> Today it is there is no protection around pciehp_enable_slot() and
> pciehp_disable_slot() to ensure that they complete before another
> hot-plug operation can be done on that particular slot.
>
> This patch introduces the slot->hotplug_lock to ensure that any
> hotplug operations (add / remove) complete before another HP event
> can begin processing on that particular slot.
>
> Signed-off-by: Rajat Jain <rajatxjain@...il.com>
> Signed-off-by: Rajat Jain <rajatjain@...iper.net>
> Signed-off-by: Guenter Roeck <groeck@...iper.net>
> ---
> Hello Bjorn,
>
>>
>> I applied these to pci/pciehp for v3.15, thanks! I dropped the "ret" decl
>> in 8/8, which I assume was the cause of the unused variable warning.
>>
>
> Thank you so much for accepting the patchset. The "ret" variable in 8/8
> was supposed to be used for holding the return value, so that the call to
> pciehp_green_led_off() could be moved to after releasing the lock. Here
> is the revised 8/8 patch (only a couple lines diff from v4). Please feel
> free to either use this, or just make that small change in
> pciehp_power_thread(). I was holding off sending this in case there were
> any other comments.
> ...
> v5: Remove the "unused variable" warning by using it to hold return value
> (Thus reducing lock hold time, by moving pciehp_green_led_off() to
> after releasing the lock)
Thanks, I folded this into my pci/pciehp branch.
> v4: same as v3, only rebased on top of 3.14-rc1
> v3: same as v2, only patch numbering changed from [4/4] to [8/8].
> v2: Same as v1, dropped the "RFC" from subject, added Guenter's signature
> v1: Initial patch
>
> drivers/pci/hotplug/pciehp.h | 1 +
> drivers/pci/hotplug/pciehp_core.c | 7 ++++++-
> drivers/pci/hotplug/pciehp_ctrl.c | 17 +++++++++++++++--
> drivers/pci/hotplug/pciehp_hpc.c | 1 +
> 4 files changed, 23 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pci/hotplug/pciehp.h b/drivers/pci/hotplug/pciehp.h
> index d8d0336..8a66866 100644
> --- a/drivers/pci/hotplug/pciehp.h
> +++ b/drivers/pci/hotplug/pciehp.h
> @@ -76,6 +76,7 @@ struct slot {
> struct hotplug_slot *hotplug_slot;
> struct delayed_work work; /* work for button event */
> struct mutex lock;
> + struct mutex hotplug_lock;
> struct workqueue_struct *wq;
> };
>
> diff --git a/drivers/pci/hotplug/pciehp_core.c b/drivers/pci/hotplug/pciehp_core.c
> index 53b58de..23b4bde 100644
> --- a/drivers/pci/hotplug/pciehp_core.c
> +++ b/drivers/pci/hotplug/pciehp_core.c
> @@ -283,8 +283,11 @@ static int pciehp_probe(struct pcie_device *dev)
> slot = ctrl->slot;
> pciehp_get_adapter_status(slot, &occupied);
> pciehp_get_power_status(slot, &poweron);
> - if (occupied && pciehp_force)
> + if (occupied && pciehp_force) {
> + mutex_lock(&slot->hotplug_lock);
> pciehp_enable_slot(slot);
> + mutex_unlock(&slot->hotplug_lock);
> + }
> /* If empty slot's power status is on, turn power off */
> if (!occupied && poweron && POWER_CTRL(ctrl))
> pciehp_power_off_slot(slot);
> @@ -328,10 +331,12 @@ static int pciehp_resume (struct pcie_device *dev)
>
> /* Check if slot is occupied */
> pciehp_get_adapter_status(slot, &status);
> + mutex_lock(&slot->hotplug_lock);
> if (status)
> pciehp_enable_slot(slot);
> else
> pciehp_disable_slot(slot);
> + mutex_unlock(&slot->hotplug_lock);
> return 0;
> }
> #endif /* PM */
> diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c
> index 3e40ec0..fec99a1 100644
> --- a/drivers/pci/hotplug/pciehp_ctrl.c
> +++ b/drivers/pci/hotplug/pciehp_ctrl.c
> @@ -293,6 +293,7 @@ static void pciehp_power_thread(struct work_struct *work)
> struct power_work_info *info =
> container_of(work, struct power_work_info, work);
> struct slot *p_slot = info->p_slot;
> + int ret;
>
> switch (info->req) {
> case DISABLE_REQ:
> @@ -300,7 +301,9 @@ static void pciehp_power_thread(struct work_struct *work)
> "Disabling domain:bus:device=%04x:%02x:00\n",
> pci_domain_nr(p_slot->ctrl->pcie->port->subordinate),
> p_slot->ctrl->pcie->port->subordinate->number);
> + mutex_lock(&p_slot->hotplug_lock);
> pciehp_disable_slot(p_slot);
> + mutex_unlock(&p_slot->hotplug_lock);
> mutex_lock(&p_slot->lock);
> p_slot->state = STATIC_STATE;
> mutex_unlock(&p_slot->lock);
> @@ -310,7 +313,10 @@ static void pciehp_power_thread(struct work_struct *work)
> "Enabling domain:bus:device=%04x:%02x:00\n",
> pci_domain_nr(p_slot->ctrl->pcie->port->subordinate),
> p_slot->ctrl->pcie->port->subordinate->number);
> - if (pciehp_enable_slot(p_slot))
> + mutex_lock(&p_slot->hotplug_lock);
> + ret = pciehp_enable_slot(p_slot);
> + mutex_unlock(&p_slot->hotplug_lock);
> + if (ret)
> pciehp_green_led_off(p_slot);
> mutex_lock(&p_slot->lock);
> p_slot->state = STATIC_STATE;
> @@ -546,6 +552,9 @@ static void interrupt_event_handler(struct work_struct *work)
> kfree(info);
> }
>
> +/*
> + * Note: This function must be called with slot->hotplug_lock held
> + */
> int pciehp_enable_slot(struct slot *p_slot)
> {
> u8 getstatus = 0;
> @@ -584,7 +593,9 @@ int pciehp_enable_slot(struct slot *p_slot)
> return rc;
> }
>
> -
> +/*
> + * Note: This function must be called with slot->hotplug_lock held
> + */
> int pciehp_disable_slot(struct slot *p_slot)
> {
> u8 getstatus = 0;
> @@ -617,7 +628,9 @@ int pciehp_sysfs_enable_slot(struct slot *p_slot)
> case STATIC_STATE:
> p_slot->state = POWERON_STATE;
> mutex_unlock(&p_slot->lock);
> + mutex_lock(&p_slot->hotplug_lock);
> retval = pciehp_enable_slot(p_slot);
> + mutex_unlock(&p_slot->hotplug_lock);
> mutex_lock(&p_slot->lock);
> p_slot->state = STATIC_STATE;
> break;
> diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
> index 55cc389..68447a1 100644
> --- a/drivers/pci/hotplug/pciehp_hpc.c
> +++ b/drivers/pci/hotplug/pciehp_hpc.c
> @@ -686,6 +686,7 @@ static int pcie_init_slot(struct controller *ctrl)
>
> slot->ctrl = ctrl;
> mutex_init(&slot->lock);
> + mutex_init(&slot->hotplug_lock);
> INIT_DELAYED_WORK(&slot->work, pciehp_queue_pushbutton_work);
> ctrl->slot = slot;
> return 0;
> --
> 1.7.9.5
>
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