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Message-ID: <20ff3d36-d0fc-4970-bc31-c267d656eb2c@ideasonboard.com>
Date: Wed, 27 Mar 2024 13:57:04 +0200
From: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
To: Sean Anderson <sean.anderson@...ux.dev>,
Laurent Pinchart <laurent.pinchart@...asonboard.com>,
Vinod Koul <vkoul@...nel.org>, dmaengine@...r.kernel.org
Cc: Michal Simek <michal.simek@....com>, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, Hyun Kwon <hyun.kwon@...inx.com>,
Tejas Upadhyay <tejasu@...inx.com>
Subject: Re: [PATCH 1/3] dma: xilinx_dpdma: Fix locking
On 08/03/2024 23:00, Sean Anderson wrote:
> There are several places where either chan->lock or chan->vchan.lock was
> not held. Add appropriate locking. This fixes lockdep warnings like
>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
Tomi
> [ 31.077578] ------------[ cut here ]------------
> [ 31.077831] WARNING: CPU: 2 PID: 40 at drivers/dma/xilinx/xilinx_dpdma.c:834 xilinx_dpdma_chan_queue_transfer+0x274/0x5e0
> [ 31.077953] Modules linked in:
> [ 31.078019] CPU: 2 PID: 40 Comm: kworker/u12:1 Not tainted 6.6.20+ #98
> [ 31.078102] Hardware name: xlnx,zynqmp (DT)
> [ 31.078169] Workqueue: events_unbound deferred_probe_work_func
> [ 31.078272] pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> [ 31.078377] pc : xilinx_dpdma_chan_queue_transfer+0x274/0x5e0
> [ 31.078473] lr : xilinx_dpdma_chan_queue_transfer+0x270/0x5e0
> [ 31.078550] sp : ffffffc083bb2e10
> [ 31.078590] x29: ffffffc083bb2e10 x28: 0000000000000000 x27: ffffff880165a168
> [ 31.078754] x26: ffffff880164e920 x25: ffffff880164eab8 x24: ffffff880164d480
> [ 31.078920] x23: ffffff880165a148 x22: ffffff880164e988 x21: 0000000000000000
> [ 31.079132] x20: ffffffc082aa3000 x19: ffffff880164e880 x18: 0000000000000000
> [ 31.079295] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
> [ 31.079453] x14: 0000000000000000 x13: ffffff8802263dc0 x12: 0000000000000001
> [ 31.079613] x11: 0001ffc083bb2e34 x10: 0001ff880164e98f x9 : 0001ffc082aa3def
> [ 31.079824] x8 : 0001ffc082aa3dec x7 : 0000000000000000 x6 : 0000000000000516
> [ 31.079982] x5 : ffffffc7f8d43000 x4 : ffffff88003c9c40 x3 : ffffffffffffffff
> [ 31.080147] x2 : ffffffc7f8d43000 x1 : 00000000000000c0 x0 : 0000000000000000
> [ 31.080307] Call trace:
> [ 31.080340] xilinx_dpdma_chan_queue_transfer+0x274/0x5e0
> [ 31.080518] xilinx_dpdma_issue_pending+0x11c/0x120
> [ 31.080595] zynqmp_disp_layer_update+0x180/0x3ac
> [ 31.080712] zynqmp_dpsub_plane_atomic_update+0x11c/0x21c
> [ 31.080825] drm_atomic_helper_commit_planes+0x20c/0x684
> [ 31.080951] drm_atomic_helper_commit_tail+0x5c/0xb0
> [ 31.081139] commit_tail+0x234/0x294
> [ 31.081246] drm_atomic_helper_commit+0x1f8/0x210
> [ 31.081363] drm_atomic_commit+0x100/0x140
> [ 31.081477] drm_client_modeset_commit_atomic+0x318/0x384
> [ 31.081634] drm_client_modeset_commit_locked+0x8c/0x24c
> [ 31.081725] drm_client_modeset_commit+0x34/0x5c
> [ 31.081812] __drm_fb_helper_restore_fbdev_mode_unlocked+0x104/0x168
> [ 31.081899] drm_fb_helper_set_par+0x50/0x70
> [ 31.081971] fbcon_init+0x538/0xc48
> [ 31.082047] visual_init+0x16c/0x23c
> [ 31.082207] do_bind_con_driver.isra.0+0x2d0/0x634
> [ 31.082320] do_take_over_console+0x24c/0x33c
> [ 31.082429] do_fbcon_takeover+0xbc/0x1b0
> [ 31.082503] fbcon_fb_registered+0x2d0/0x34c
> [ 31.082663] register_framebuffer+0x27c/0x38c
> [ 31.082767] __drm_fb_helper_initial_config_and_unlock+0x5c0/0x91c
> [ 31.082939] drm_fb_helper_initial_config+0x50/0x74
> [ 31.083012] drm_fbdev_dma_client_hotplug+0xb8/0x108
> [ 31.083115] drm_client_register+0xa0/0xf4
> [ 31.083195] drm_fbdev_dma_setup+0xb0/0x1cc
> [ 31.083293] zynqmp_dpsub_drm_init+0x45c/0x4e0
> [ 31.083431] zynqmp_dpsub_probe+0x444/0x5e0
> [ 31.083616] platform_probe+0x8c/0x13c
> [ 31.083713] really_probe+0x258/0x59c
> [ 31.083793] __driver_probe_device+0xc4/0x224
> [ 31.083878] driver_probe_device+0x70/0x1c0
> [ 31.083961] __device_attach_driver+0x108/0x1e0
> [ 31.084052] bus_for_each_drv+0x9c/0x100
> [ 31.084125] __device_attach+0x100/0x298
> [ 31.084207] device_initial_probe+0x14/0x20
> [ 31.084292] bus_probe_device+0xd8/0xdc
> [ 31.084368] deferred_probe_work_func+0x11c/0x180
> [ 31.084451] process_one_work+0x3ac/0x988
> [ 31.084643] worker_thread+0x398/0x694
> [ 31.084752] kthread+0x1bc/0x1c0
> [ 31.084848] ret_from_fork+0x10/0x20
> [ 31.084932] irq event stamp: 64549
> [ 31.084970] hardirqs last enabled at (64548): [<ffffffc081adf35c>] _raw_spin_unlock_irqrestore+0x80/0x90
> [ 31.085157] hardirqs last disabled at (64549): [<ffffffc081adf010>] _raw_spin_lock_irqsave+0xc0/0xdc
> [ 31.085277] softirqs last enabled at (64503): [<ffffffc08001071c>] __do_softirq+0x47c/0x500
> [ 31.085390] softirqs last disabled at (64498): [<ffffffc080017134>] ____do_softirq+0x10/0x1c
> [ 31.085501] ---[ end trace 0000000000000000 ]---
>
> Fixes: 7cbb0c63de3f ("dmaengine: xilinx: dpdma: Add the Xilinx DisplayPort DMA engine driver")
> Signed-off-by: Sean Anderson <sean.anderson@...ux.dev>
> ---
>
> drivers/dma/xilinx/xilinx_dpdma.c | 13 ++++++++++---
> 1 file changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/dma/xilinx/xilinx_dpdma.c b/drivers/dma/xilinx/xilinx_dpdma.c
> index b82815e64d24..eb0637d90342 100644
> --- a/drivers/dma/xilinx/xilinx_dpdma.c
> +++ b/drivers/dma/xilinx/xilinx_dpdma.c
> @@ -214,7 +214,8 @@ struct xilinx_dpdma_tx_desc {
> * @running: true if the channel is running
> * @first_frame: flag for the first frame of stream
> * @video_group: flag if multi-channel operation is needed for video channels
> - * @lock: lock to access struct xilinx_dpdma_chan
> + * @lock: lock to access struct xilinx_dpdma_chan. Must be taken before
> + * @vchan.lock, if both are to be held.
> * @desc_pool: descriptor allocation pool
> * @err_task: error IRQ bottom half handler
> * @desc: References to descriptors being processed
> @@ -1097,12 +1098,14 @@ static void xilinx_dpdma_chan_vsync_irq(struct xilinx_dpdma_chan *chan)
> * Complete the active descriptor, if any, promote the pending
> * descriptor to active, and queue the next transfer, if any.
> */
> + spin_lock(&chan->vchan.lock);
> if (chan->desc.active)
> vchan_cookie_complete(&chan->desc.active->vdesc);
> chan->desc.active = pending;
> chan->desc.pending = NULL;
>
> xilinx_dpdma_chan_queue_transfer(chan);
> + spin_unlock(&chan->vchan.lock);
>
> out:
> spin_unlock_irqrestore(&chan->lock, flags);
> @@ -1264,10 +1267,12 @@ static void xilinx_dpdma_issue_pending(struct dma_chan *dchan)
> struct xilinx_dpdma_chan *chan = to_xilinx_chan(dchan);
> unsigned long flags;
>
> - spin_lock_irqsave(&chan->vchan.lock, flags);
> + spin_lock_irqsave(&chan->lock, flags);
> + spin_lock(&chan->vchan.lock);
> if (vchan_issue_pending(&chan->vchan))
> xilinx_dpdma_chan_queue_transfer(chan);
> - spin_unlock_irqrestore(&chan->vchan.lock, flags);
> + spin_unlock(&chan->vchan.lock);
> + spin_unlock_irqrestore(&chan->lock, flags);
> }
>
> static int xilinx_dpdma_config(struct dma_chan *dchan,
> @@ -1495,7 +1500,9 @@ static void xilinx_dpdma_chan_err_task(struct tasklet_struct *t)
> XILINX_DPDMA_EINTR_CHAN_ERR_MASK << chan->id);
>
> spin_lock_irqsave(&chan->lock, flags);
> + spin_lock(&chan->vchan.lock);
> xilinx_dpdma_chan_queue_transfer(chan);
> + spin_unlock(&chan->vchan.lock);
> spin_unlock_irqrestore(&chan->lock, flags);
> }
>
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