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Subject[PATCH 5.4 072/111] dmaengine: owl: Use correct lock in owl_dma_get_pchan()
Date
From: Cristian Ciocaltea <cristian.ciocaltea@gmail.com>

commit f8f482deb078389b42768b2193e050a81aae137d upstream.

When the kernel is built with lockdep support and the owl-dma driver is
used, the following message is shown:

[ 2.496939] INFO: trying to register non-static key.
[ 2.501889] the code is fine but needs lockdep annotation.
[ 2.507357] turning off the locking correctness validator.
[ 2.512834] CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.6.3+ #15
[ 2.519084] Hardware name: Generic DT based system
[ 2.523878] Workqueue: events_freezable mmc_rescan
[ 2.528681] [<801127f0>] (unwind_backtrace) from [<8010da58>] (show_stack+0x10/0x14)
[ 2.536420] [<8010da58>] (show_stack) from [<8080fbe8>] (dump_stack+0xb4/0xe0)
[ 2.543645] [<8080fbe8>] (dump_stack) from [<8017efa4>] (register_lock_class+0x6f0/0x718)
[ 2.551816] [<8017efa4>] (register_lock_class) from [<8017b7d0>] (__lock_acquire+0x78/0x25f0)
[ 2.560330] [<8017b7d0>] (__lock_acquire) from [<8017e5e4>] (lock_acquire+0xd8/0x1f4)
[ 2.568159] [<8017e5e4>] (lock_acquire) from [<80831fb0>] (_raw_spin_lock_irqsave+0x3c/0x50)
[ 2.576589] [<80831fb0>] (_raw_spin_lock_irqsave) from [<8051b5fc>] (owl_dma_issue_pending+0xbc/0x120)
[ 2.585884] [<8051b5fc>] (owl_dma_issue_pending) from [<80668cbc>] (owl_mmc_request+0x1b0/0x390)
[ 2.594655] [<80668cbc>] (owl_mmc_request) from [<80650ce0>] (mmc_start_request+0x94/0xbc)
[ 2.602906] [<80650ce0>] (mmc_start_request) from [<80650ec0>] (mmc_wait_for_req+0x64/0xd0)
[ 2.611245] [<80650ec0>] (mmc_wait_for_req) from [<8065aa10>] (mmc_app_send_scr+0x10c/0x144)
[ 2.619669] [<8065aa10>] (mmc_app_send_scr) from [<80659b3c>] (mmc_sd_setup_card+0x4c/0x318)
[ 2.628092] [<80659b3c>] (mmc_sd_setup_card) from [<80659f0c>] (mmc_sd_init_card+0x104/0x430)
[ 2.636601] [<80659f0c>] (mmc_sd_init_card) from [<8065a3e0>] (mmc_attach_sd+0xcc/0x16c)
[ 2.644678] [<8065a3e0>] (mmc_attach_sd) from [<8065301c>] (mmc_rescan+0x3ac/0x40c)
[ 2.652332] [<8065301c>] (mmc_rescan) from [<80143244>] (process_one_work+0x2d8/0x780)
[ 2.660239] [<80143244>] (process_one_work) from [<80143730>] (worker_thread+0x44/0x598)
[ 2.668323] [<80143730>] (worker_thread) from [<8014b5f8>] (kthread+0x148/0x150)
[ 2.675708] [<8014b5f8>] (kthread) from [<801010b4>] (ret_from_fork+0x14/0x20)
[ 2.682912] Exception stack(0xee8fdfb0 to 0xee8fdff8)
[ 2.687954] dfa0: 00000000 00000000 00000000 00000000
[ 2.696118] dfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[ 2.704277] dfe0: 00000000 00000000 00000000 00000000 00000013 00000000

The obvious fix would be to use 'spin_lock_init()' on 'pchan->lock'
before attempting to call 'spin_lock_irqsave()' in 'owl_dma_get_pchan()'.

However, according to Manivannan Sadhasivam, 'pchan->lock' was supposed
to only protect 'pchan->vchan' while 'od->lock' does a similar job in
'owl_dma_terminate_pchan()'.

Therefore, this patch substitutes 'pchan->lock' with 'od->lock' and
removes the 'lock' attribute in 'owl_dma_pchan' struct.

Fixes: 47e20577c24d ("dmaengine: Add Actions Semi Owl family S900 DMA driver")
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@gmail.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Acked-by: Andreas Färber <afaerber@suse.de>
Link: https://lore.kernel.org/r/c6e6cdaca252b5364bd294093673951036488cf0.1588439073.git.cristian.ciocaltea@gmail.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/dma/owl-dma.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)

--- a/drivers/dma/owl-dma.c
+++ b/drivers/dma/owl-dma.c
@@ -175,13 +175,11 @@ struct owl_dma_txd {
* @id: physical index to this channel
* @base: virtual memory base for the dma channel
* @vchan: the virtual channel currently being served by this physical channel
- * @lock: a lock to use when altering an instance of this struct
*/
struct owl_dma_pchan {
u32 id;
void __iomem *base;
struct owl_dma_vchan *vchan;
- spinlock_t lock;
};

/**
@@ -437,14 +435,14 @@ static struct owl_dma_pchan *owl_dma_get
for (i = 0; i < od->nr_pchans; i++) {
pchan = &od->pchans[i];

- spin_lock_irqsave(&pchan->lock, flags);
+ spin_lock_irqsave(&od->lock, flags);
if (!pchan->vchan) {
pchan->vchan = vchan;
- spin_unlock_irqrestore(&pchan->lock, flags);
+ spin_unlock_irqrestore(&od->lock, flags);
break;
}

- spin_unlock_irqrestore(&pchan->lock, flags);
+ spin_unlock_irqrestore(&od->lock, flags);
}

return pchan;

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