[PATCH] mailbox: PCC: Fix lockdep warning when request PCC channel
From: Hoan Tran <hidden>
Date: 2016-10-14 22:53:06
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. Adding a mutex to protect critical section of this function. Beside of that, spinlock is still used to protect the data of channel. Signed-off-by: Hoan Tran <redacted> --- drivers/mailbox/pcc.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
index 08c87fa..b6cece0 100644
--- a/drivers/mailbox/pcc.c
+++ b/drivers/mailbox/pcc.c@@ -81,6 +81,8 @@ static int *pcc_doorbell_irq; static struct mbox_controller pcc_mbox_ctrl = {}; +static DEFINE_MUTEX(pcc_con_mutex); + /** * get_pcc_channel - Given a PCC subspace idx, get * the respective mbox_channel.
@@ -243,6 +245,7 @@ struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl, struct mbox_chan *chan; unsigned long flags; + mutex_lock(&pcc_con_mutex); /* * Each PCC Subspace is a Mailbox Channel. * The PCC Clients get their PCC Subspace ID
@@ -254,6 +257,7 @@ struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl, if (IS_ERR(chan) || chan->cl) { dev_err(dev, "Channel not found for idx: %d\n", subspace_id); + mutex_unlock(&pcc_con_mutex); return ERR_PTR(-EBUSY); }
@@ -267,6 +271,8 @@ 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;
@@ -279,7 +285,7 @@ struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl, } } - spin_unlock_irqrestore(&chan->lock, flags); + mutex_unlock(&pcc_con_mutex); return chan; }
--
1.9.1