Hi, On Tue, Apr 28, 2020 at 01:56:12PM +0300, Cristian Ciocaltea wrote: > When the kernel is build 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 required fix is to use spin_lock_init() on the pchan lock before > attempting to call any spin_lock_irqsave() in owl_dma_get_pchan(). > Right, this is a bug. But while looking at the code now, I feel that we don't need 'pchan->lock'. The idea was to protect 'pchan->vchan', but I think 'od->lock' is the better candidate for that since it already protects it in 'owl_dma_terminate_pchan'. So I'd be happy if you remove the lock from 'pchan' and just directly use the one in 'od'. Out of curiosity, on which platform you're testing this? Thanks, Mani > Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@xxxxxxxxx> > --- > drivers/dma/owl-dma.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/dma/owl-dma.c b/drivers/dma/owl-dma.c > index c683051257fd..d9d0f0488e70 100644 > --- a/drivers/dma/owl-dma.c > +++ b/drivers/dma/owl-dma.c > @@ -1131,6 +1131,7 @@ static int owl_dma_probe(struct platform_device *pdev) > > pchan->id = i; > pchan->base = od->base + OWL_DMA_CHAN_BASE(i); > + spin_lock_init(&pchan->lock); > } > > /* Init virtual channel */ > -- > 2.26.2 >
