Re: [PATCH v3] mailbox: PCC: Fix lockdep warning when request PCC channel
From: Hoan Tran
Date: Thu Nov 10 2016 - 01:39:56 EST
Hi All,
On Thu, Oct 27, 2016 at 3:34 PM, Hoan Tran <hotran@xxxxxxx> wrote:
> This patch fixes the lockdep warning below
>
> [ 7.229767] DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags))
> [ 7.229776] ------------[ cut here ]------------
> [ 7.229787] WARNING: CPU: 1 PID: 1 at linux-next/kernel/locking/lockdep.c:2876 loc
> kdep_trace_alloc+0xe0/0xf0
> [ 7.229790] Modules linked in:
> [ 7.229793]
> [ 7.229798] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.8.0-11756-g86c5152 #46
> ...
> [ 7.229900] Call trace:
> [ 7.229903] Exception stack(0xffff8007da837890 to 0xffff8007da8379c0)
> [ 7.229906] 7880: ffff8007da834000 0001000000000000
> [ 7.229909] 78a0: ffff8007da837a70 ffff0000081111a0 00000000600000c5 000000000000003d
> [ 7.229912] 78c0: 9374bc6a7f3c7832 0000000000381878 ffff000009db7ab8 000000000000002f
> [ 7.229915] 78e0: ffff00000811aabc ffff000008be2548 ffff8007da837990 ffff00000811adf8
> [ 7.229918] 7900: ffff8007da834000 00000000024080c0 00000000000000c0 ffff000009021000
> [ 7.229921] 7920: 0000000000000000 0000000000000000 ffff000008c8f7c8 ffff8007da579810
> [ 7.229923] 7940: 000000000000002f ffff8007da858000 0000000000000000 0000000000000001
> [ 7.229926] 7960: 0000000000000001 0000000000000000 ffff00000811a468 0000000000000002
> [ 7.229929] 7980: 656c62617369645f 0000000000038187 00000000000000ee ffff8007da837850
> [ 7.229932] 79a0: ffff000009db50c0 ffff000009db569d 0000000000000006 ffff000089db568f
> [ 7.229936] [<ffff0000081111a0>] lockdep_trace_alloc+0xe0/0xf0
> [ 7.229940] [<ffff0000081f4950>] __kmalloc_track_caller+0x50/0x250
> [ 7.229945] [<ffff00000857c088>] devres_alloc_node+0x28/0x60
> [ 7.229949] [<ffff0000081220e0>] devm_request_threaded_irq+0x50/0xe0
> [ 7.229955] [<ffff0000087e6220>] pcc_mbox_request_channel+0x110/0x170
> [ 7.229960] [<ffff0000084b2660>] acpi_cppc_processor_probe+0x264/0x414
> [ 7.229963] [<ffff0000084ae9f4>] __acpi_processor_start+0x28/0xa0
> [ 7.229966] [<ffff0000084aeab0>] acpi_processor_start+0x44/0x54
> [ 7.229970] [<ffff00000857897c>] driver_probe_device+0x1fc/0x2b0
> [ 7.229974] [<ffff000008578ae4>] __driver_attach+0xb4/0xc0
> [ 7.229977] [<ffff00000857683c>] bus_for_each_dev+0x5c/0xa0
> [ 7.229980] [<ffff000008578110>] driver_attach+0x20/0x30
> [ 7.229983] [<ffff000008577c20>] bus_add_driver+0x110/0x230
> [ 7.229987] [<ffff000008579320>] driver_register+0x60/0x100
> [ 7.229991] [<ffff000008d478b8>] acpi_processor_driver_init+0x2c/0xb0
> [ 7.229996] [<ffff000008083168>] do_one_initcall+0x38/0x130
> [ 7.230000] [<ffff000008d20d6c>] kernel_init_freeable+0x210/0x2b4
> [ 7.230004] [<ffff000008945d90>] kernel_init+0x10/0x110
> [ 7.230007] [<ffff000008082e80>] ret_from_fork+0x10/0x50
>
> It's because the spinlock inside pcc_mbox_request_channel() is
> kept too long. This patch releases spinlock before request_irq()
> and free_irq() to fix this issue as spinlock is only needed to
> protect the channel data.
>
> Signed-off-by: Hoan Tran <hotran@xxxxxxx>
> ---
> v3
> * Free mailbox irq before reset the channel data
> * Free channel if it fails to request the mailbox irq
>
> v2
> * Release spinlock before request_irq() and free_irq() instead of
> using mutex
>
>
> drivers/mailbox/pcc.c | 70 +++++++++++++++++++++++++--------------------------
> 1 file changed, 35 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
> index 08c87fa..4b2f061 100644
> --- a/drivers/mailbox/pcc.c
> +++ b/drivers/mailbox/pcc.c
> @@ -224,6 +224,38 @@ static irqreturn_t pcc_mbox_irq(int irq, void *p)
> }
>
> /**
> + * pcc_mbox_free_channel - Clients call this to free their Channel.
> + *
> + * @chan: Pointer to the mailbox channel as returned by
> + * pcc_mbox_request_channel()
> + */
> +void pcc_mbox_free_channel(struct mbox_chan *chan)
> +{
> + u32 id = chan - pcc_mbox_channels;
> + unsigned long flags;
> +
> + if (!chan || !chan->cl)
> + return;
> +
> + if (id >= pcc_mbox_ctrl.num_chans) {
> + pr_debug("pcc_mbox_free_channel: Invalid mbox_chan passed\n");
> + return;
> + }
> +
> + if (pcc_doorbell_irq[id] > 0)
> + devm_free_irq(chan->mbox->dev, pcc_doorbell_irq[id], chan);
> +
> + spin_lock_irqsave(&chan->lock, flags);
> + chan->cl = NULL;
> + chan->active_req = NULL;
> + if (chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK))
> + chan->txdone_method = TXDONE_BY_POLL;
> +
> + spin_unlock_irqrestore(&chan->lock, flags);
> +}
> +EXPORT_SYMBOL_GPL(pcc_mbox_free_channel);
> +
> +/**
> * pcc_mbox_request_channel - PCC clients call this function to
> * request a pointer to their PCC subspace, from which they
> * can get the details of communicating with the remote.
> @@ -267,6 +299,8 @@ struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl,
> if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
> chan->txdone_method |= TXDONE_BY_ACK;
>
> + spin_unlock_irqrestore(&chan->lock, flags);
> +
> if (pcc_doorbell_irq[subspace_id] > 0) {
> int rc;
>
> @@ -275,50 +309,16 @@ struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl,
> if (unlikely(rc)) {
> dev_err(dev, "failed to register PCC interrupt %d\n",
> pcc_doorbell_irq[subspace_id]);
> + pcc_mbox_free_channel(chan);
> chan = ERR_PTR(rc);
> }
> }
>
> - spin_unlock_irqrestore(&chan->lock, flags);
> -
> return chan;
> }
> EXPORT_SYMBOL_GPL(pcc_mbox_request_channel);
>
> /**
> - * pcc_mbox_free_channel - Clients call this to free their Channel.
> - *
> - * @chan: Pointer to the mailbox channel as returned by
> - * pcc_mbox_request_channel()
> - */
> -void pcc_mbox_free_channel(struct mbox_chan *chan)
> -{
> - u32 id = chan - pcc_mbox_channels;
> - unsigned long flags;
> -
> - if (!chan || !chan->cl)
> - return;
> -
> - if (id >= pcc_mbox_ctrl.num_chans) {
> - pr_debug("pcc_mbox_free_channel: Invalid mbox_chan passed\n");
> - return;
> - }
> -
> - spin_lock_irqsave(&chan->lock, flags);
> - chan->cl = NULL;
> - chan->active_req = NULL;
> - if (chan->txdone_method == (TXDONE_BY_POLL | TXDONE_BY_ACK))
> - chan->txdone_method = TXDONE_BY_POLL;
> -
> - if (pcc_doorbell_irq[id] > 0)
> - devm_free_irq(chan->mbox->dev, pcc_doorbell_irq[id], chan);
> -
> - spin_unlock_irqrestore(&chan->lock, flags);
> -}
> -EXPORT_SYMBOL_GPL(pcc_mbox_free_channel);
> -
> -
> -/**
> * pcc_send_data - Called from Mailbox Controller code. Used
> * here only to ring the channel doorbell. The PCC client
> * specific read/write is done in the client driver in
> --
> 1.9.1
>
Do you have any comments about this patch ?
Thanks
Hoan