imx-drm: imx-drm-core: Fix circular locking dependency
Booting a mx6 with CONFIG_PROVE_LOCKING we get: ====================================================== [ INFO: possible circular locking dependency detected ] 3.12.0-rc4-next-20131009+ #34 Not tainted ------------------------------------------------------- swapper/0/1 is trying to acquire lock: (&imx_drm_device->mutex){+.+.+.}, at: [<804575a8>] imx_drm_encoder_get_mux_id+0x28/0x98 but task is already holding lock: (&crtc->mutex){+.+...}, at: [<802fe778>] drm_modeset_lock_all+0x40/0x54 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&crtc->mutex){+.+...}: [<800777d0>] __lock_acquire+0x18d4/0x1c24 [<80077fec>] lock_acquire+0x68/0x7c [<805ead5c>] _mutex_lock_nest_lock+0x58/0x3a8 [<802fec50>] drm_crtc_init+0x48/0xa8 [<80457c88>] imx_drm_add_crtc+0xd4/0x144 [<8045e2e8>] ipu_drm_probe+0x114/0x1fc [<80312278>] platform_drv_probe+0x20/0x50 [<80310c68>] driver_probe_device+0x110/0x22c [<80310e20>] __driver_attach+0x9c/0xa0 [<8030f218>] bus_for_each_dev+0x5c/0x90 [<80310750>] driver_attach+0x20/0x28 [<8031034c>] bus_add_driver+0xdc/0x1dc [<803114d8>] driver_register+0x80/0xfc [<80312198>] __platform_driver_register+0x50/0x64 [<808172fc>] ipu_drm_driver_init+0x18/0x20 [<800088c0>] do_one_initcall+0xfc/0x160 [<807e7c5c>] kernel_init_freeable+0x104/0x1d4 [<805e2930>] kernel_init+0x10/0xec [<8000ea68>] ret_from_fork+0x14/0x2c -> #1 (&dev->mode_config.mutex){+.+.+.}: [<800777d0>] __lock_acquire+0x18d4/0x1c24 [<80077fec>] lock_acquire+0x68/0x7c [<805eb100>] mutex_lock_nested+0x54/0x3a4 [<802fe758>] drm_modeset_lock_all+0x20/0x54 [<802fead4>] drm_encoder_init+0x20/0x7c [<80457ae4>] imx_drm_add_encoder+0x88/0xec [<80459838>] imx_ldb_probe+0x344/0x4fc [<80312278>] platform_drv_probe+0x20/0x50 [<80310c68>] driver_probe_device+0x110/0x22c [<80310e20>] __driver_attach+0x9c/0xa0 [<8030f218>] bus_for_each_dev+0x5c/0x90 [<80310750>] driver_attach+0x20/0x28 [<8031034c>] bus_add_driver+0xdc/0x1dc [<803114d8>] driver_register+0x80/0xfc [<80312198>] __platform_driver_register+0x50/0x64 [<8081722c>] imx_ldb_driver_init+0x18/0x20 [<800088c0>] do_one_initcall+0xfc/0x160 [<807e7c5c>] kernel_init_freeable+0x104/0x1d4 [<805e2930>] kernel_init+0x10/0xec [<8000ea68>] ret_from_fork+0x14/0x2c -> #0 (&imx_drm_device->mutex){+.+.+.}: [<805e510c>] print_circular_bug+0x74/0x2e0 [<80077ad0>] __lock_acquire+0x1bd4/0x1c24 [<80077fec>] lock_acquire+0x68/0x7c [<805eb100>] mutex_lock_nested+0x54/0x3a4 [<804575a8>] imx_drm_encoder_get_mux_id+0x28/0x98 [<80459a98>] imx_ldb_encoder_prepare+0x34/0x114 [<802ef724>] drm_crtc_helper_set_mode+0x1f0/0x4c0 [<802f0344>] drm_crtc_helper_set_config+0x828/0x99c [<802ff270>] drm_mode_set_config_internal+0x5c/0xdc [<802eebe0>] drm_fb_helper_set_par+0x50/0xb4 [<802af580>] fbcon_init+0x490/0x500 [<802dd104>] visual_init+0xa8/0xf8 [<802df414>] do_bind_con_driver+0x140/0x37c [<802df764>] do_take_over_console+0x114/0x1c4 [<802af65c>] do_fbcon_takeover+0x6c/0xd4 [<802b2b30>] fbcon_event_notify+0x7c8/0x818 [<80049954>] notifier_call_chain+0x4c/0x8c [<80049cd8>] __blocking_notifier_call_chain+0x50/0x68 [<80049d10>] blocking_notifier_call_chain+0x20/0x28 [<802a75f0>] fb_notifier_call_chain+0x1c/0x24 [<802a9224>] register_framebuffer+0x188/0x268 [<802ee994>] drm_fb_helper_initial_config+0x2bc/0x4b8 [<802f118c>] drm_fbdev_cma_init+0x7c/0xec [<80817288>] imx_fb_helper_init+0x54/0x90 [<800088c0>] do_one_initcall+0xfc/0x160 [<807e7c5c>] kernel_init_freeable+0x104/0x1d4 [<805e2930>] kernel_init+0x10/0xec [<8000ea68>] ret_from_fork+0x14/0x2c other info that might help us debug this: Chain exists of: &imx_drm_device->mutex --> &dev->mode_config.mutex --> &crtc->mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&crtc->mutex); lock(&dev->mode_config.mutex); lock(&crtc->mutex); lock(&imx_drm_device->mutex); *** DEADLOCK *** 6 locks held by swapper/0/1: #0: (registration_lock){+.+.+.}, at: [<802a90bc>] register_framebuffer+0x20/0x268 #1: (&fb_info->lock){+.+.+.}, at: [<802a7a90>] lock_fb_info+0x20/0x44 #2: (console_lock){+.+.+.}, at: [<802a9218>] register_framebuffer+0x17c/0x268 #3: ((fb_notifier_list).rwsem){.+.+.+}, at: [<80049cbc>] __blocking_notifier_call_chain+0x34/0x68 #4: (&dev->mode_config.mutex){+.+.+.}, at: [<802fe758>] drm_modeset_lock_all+0x20/0x54 #5: (&crtc->mutex){+.+...}, at: [<802fe778>] drm_modeset_lock_all+0x40/0x54 In order to avoid this lockdep warning, remove the locking from imx_drm_encoder_get_mux_id() and imx_drm_crtc_panel_format_pins(). Tested on a mx6sabrelite and mx53qsb. Reported-by: Russell King <rmk+kernel@arm.linux.org.uk> Tested-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Fabio Estevam
Greg Kroah-Hartman
parent
4ad0fdb0e2
commit
c35d6a37bd
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@ -110,18 +110,12 @@ int imx_drm_crtc_panel_format_pins(struct drm_crtc *crtc, u32 encoder_type,
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struct imx_drm_crtc *imx_crtc;
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struct imx_drm_crtc_helper_funcs *helper;
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mutex_lock(&imxdrm->mutex);
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list_for_each_entry(imx_crtc, &imxdrm->crtc_list, list)
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if (imx_crtc->crtc == crtc)
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goto found;
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mutex_unlock(&imxdrm->mutex);
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return -EINVAL;
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found:
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mutex_unlock(&imxdrm->mutex);
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helper = &imx_crtc->imx_drm_helper_funcs;
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if (helper->set_interface_pix_fmt)
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return helper->set_interface_pix_fmt(crtc,
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@ -647,20 +641,14 @@ int imx_drm_encoder_get_mux_id(struct imx_drm_encoder *imx_drm_encoder,
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struct imx_drm_crtc *imx_crtc;
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int i = 0;
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mutex_lock(&imxdrm->mutex);
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list_for_each_entry(imx_crtc, &imxdrm->crtc_list, list) {
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if (imx_crtc->crtc == crtc)
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goto found;
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i++;
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}
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mutex_unlock(&imxdrm->mutex);
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return -EINVAL;
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found:
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mutex_unlock(&imxdrm->mutex);
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return i;
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}
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EXPORT_SYMBOL_GPL(imx_drm_encoder_get_mux_id);
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