| Message ID | 1445767774-24001-2-git-send-email-geert+renesas@glider.be (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Geert Uytterhoeven |
| Headers | show |
On Sun, Oct 25, 2015 at 11:09:33AM +0100, Geert Uytterhoeven wrote: > If CONFIG_PREEMPT=y: > > Unable to handle kernel NULL pointer dereference at virtual address 00000014 > pgd = c0003000 > [00000014] *pgd=80000040004003, *pmd=00000000 > Internal error: Oops: 206 [#1] PREEMPT SMP ARM > Modules linked in: > CPU: 0 PID: 17 Comm: kworker/0:1 Tainted: G W 4.3.0-rc3-koelsch-022 > 71-g705498fc5e6a5da8-dirty #1789 > Hardware name: Generic R8A7791 (Flattened Device Tree) > Workqueue: pm pm_runtime_work > task: ef578e40 ti: ef57a000 task.ti: ef57a000 > PC is at usb_dmac_chan_halt+0xc/0xc0 > LR is at usb_dmac_runtime_suspend+0x28/0x38 > pc : [<c023c880>] lr : [<c023c95c>] psr: 80000113 > sp : ef57bdf8 ip : 00000008 fp : 00000003 > r10: 00000008 r9 : c06ab928 r8 : ef49e810 > r7 : 00000000 r6 : 000000ac r5 : ef770010 r4 : 00000000 > r3 : 00000000 r2 : 8ffc2b84 r1 : 00000000 r0 : ef770010 > Flags: Nzcv IRQs on FIQs on Mode SVC_32 ISA ARM Segment kernel > Control: 30c5307d Table: 40003000 DAC: fffffffd > Process kworker/0:1 (pid: 17, stack limit = 0xef57a210) > Stack: (0xef57bdf8 to 0xef57c000) > > [... > > [<c023c880>] (usb_dmac_chan_halt) from [<c023c95c>] (usb_dmac_runtime_suspend+0x28/0x38) > [<c023c95c>] (usb_dmac_runtime_suspend) from [<c027b25c>] (pm_genpd_runtime_suspend+0x74/0x23c) > > This happens because usb_dmac_probe() calls pm_runtime_put() before > usb_dmac_chan_probe(), leading to the device being suspended before the > DMA channels are initialized, causing a NULL pointer dereference. > > Move the call to pm_runtime_put() to the end of usb_dmac_probe() to fix > this. > > Add a check to usb_dmac_runtime_suspend() to prevent the crash from > happening in the error path. This worked, applied both now Thanks
diff --git a/drivers/dma/sh/usb-dmac.c b/drivers/dma/sh/usb-dmac.c index ebd8a5f398b08ee2..f305738b5adf8cc9 100644 --- a/drivers/dma/sh/usb-dmac.c +++ b/drivers/dma/sh/usb-dmac.c @@ -679,8 +679,11 @@ static int usb_dmac_runtime_suspend(struct device *dev) struct usb_dmac *dmac = dev_get_drvdata(dev); int i; - for (i = 0; i < dmac->n_channels; ++i) + for (i = 0; i < dmac->n_channels; ++i) { + if (!dmac->channels[i].iomem) + break; usb_dmac_chan_halt(&dmac->channels[i]); + } return 0; } @@ -803,7 +806,6 @@ static int usb_dmac_probe(struct platform_device *pdev) } ret = usb_dmac_init(dmac); - pm_runtime_put(&pdev->dev); if (ret) { dev_err(&pdev->dev, "failed to reset device\n"); @@ -851,10 +853,12 @@ static int usb_dmac_probe(struct platform_device *pdev) if (ret < 0) goto error; + pm_runtime_put(&pdev->dev); return 0; error: of_dma_controller_free(pdev->dev.of_node); + pm_runtime_put(&pdev->dev); pm_runtime_disable(&pdev->dev); return ret; }
If CONFIG_PREEMPT=y: Unable to handle kernel NULL pointer dereference at virtual address 00000014 pgd = c0003000 [00000014] *pgd=80000040004003, *pmd=00000000 Internal error: Oops: 206 [#1] PREEMPT SMP ARM Modules linked in: CPU: 0 PID: 17 Comm: kworker/0:1 Tainted: G W 4.3.0-rc3-koelsch-022 71-g705498fc5e6a5da8-dirty #1789 Hardware name: Generic R8A7791 (Flattened Device Tree) Workqueue: pm pm_runtime_work task: ef578e40 ti: ef57a000 task.ti: ef57a000 PC is at usb_dmac_chan_halt+0xc/0xc0 LR is at usb_dmac_runtime_suspend+0x28/0x38 pc : [<c023c880>] lr : [<c023c95c>] psr: 80000113 sp : ef57bdf8 ip : 00000008 fp : 00000003 r10: 00000008 r9 : c06ab928 r8 : ef49e810 r7 : 00000000 r6 : 000000ac r5 : ef770010 r4 : 00000000 r3 : 00000000 r2 : 8ffc2b84 r1 : 00000000 r0 : ef770010 Flags: Nzcv IRQs on FIQs on Mode SVC_32 ISA ARM Segment kernel Control: 30c5307d Table: 40003000 DAC: fffffffd Process kworker/0:1 (pid: 17, stack limit = 0xef57a210) Stack: (0xef57bdf8 to 0xef57c000) [... [<c023c880>] (usb_dmac_chan_halt) from [<c023c95c>] (usb_dmac_runtime_suspend+0x28/0x38) [<c023c95c>] (usb_dmac_runtime_suspend) from [<c027b25c>] (pm_genpd_runtime_suspend+0x74/0x23c) This happens because usb_dmac_probe() calls pm_runtime_put() before usb_dmac_chan_probe(), leading to the device being suspended before the DMA channels are initialized, causing a NULL pointer dereference. Move the call to pm_runtime_put() to the end of usb_dmac_probe() to fix this. Add a check to usb_dmac_runtime_suspend() to prevent the crash from happening in the error path. Reported-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Tested-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> --- v2: - Add Tested-by. drivers/dma/sh/usb-dmac.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)