On Thu, Oct 08, 2020 at 05:27:49PM +0100, John Keeping wrote:
> With threadirqs, stmmac_interrupt() is called on a thread with hardirqs
> enabled so we cannot call __napi_schedule_irqoff(). Under lockdep it
> leads to:
>
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 285 at kernel/softirq.c:598
> __raise_softirq_irqoff+0x6c/0x1c8
> IRQs not disabled as expected
> Modules linked in: brcmfmac hci_uart btbcm cfg80211 brcmutil
> CPU: 0 PID: 285 Comm: irq/41-eth0 Not tainted 5.4.69-rt39 #1
> Hardware name: Rockchip (Device Tree)
> [<c0110d3c>] (unwind_backtrace) from [<c010c284>] (show_stack+0x10/0x14)
> [<c010c284>] (show_stack) from [<c0855504>] (dump_stack+0xa8/0xe0)
> [<c0855504>] (dump_stack) from [<c0120a9c>] (__warn+0xe0/0xfc)
> [<c0120a9c>] (__warn) from [<c0120e80>] (warn_slowpath_fmt+0x7c/0xa4)
> [<c0120e80>] (warn_slowpath_fmt) from [<c01278c8>]
> (__raise_softirq_irqoff+0x6c/0x1c8)
> [<c01278c8>] (__raise_softirq_irqoff) from [<c056bccc>]
> (stmmac_interrupt+0x388/0x4e0)
> [<c056bccc>] (stmmac_interrupt) from [<c0178714>]
> (irq_forced_thread_fn+0x28/0x64)
> [<c0178714>] (irq_forced_thread_fn) from [<c0178924>]
> (irq_thread+0x124/0x260)
> [<c0178924>] (irq_thread) from [<c0142ee8>] (kthread+0x154/0x164)
> [<c0142ee8>] (kthread) from [<c01010bc>] (ret_from_fork+0x14/0x38)
> Exception stack(0xeb7b5fb0 to 0xeb7b5ff8)
> 5fa0: 00000000 00000000 00000000
> 00000000
> 5fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> 00000000
> 5fe0: 00000000 00000000 00000000 00000000 00000013 00000000
> irq event stamp: 48
> hardirqs last enabled at (50): [<c085c200>] prb_unlock+0x7c/0x8c
> hardirqs last disabled at (51): [<c085c0dc>] prb_lock+0x58/0x100
> softirqs last enabled at (0): [<c011e770>] copy_process+0x550/0x1654
> softirqs last disabled at (25): [<c01786ec>]
> irq_forced_thread_fn+0x0/0x64
> ---[ end trace 0000000000000002 ]---
>
> Use __napi_schedule() instead which will save & restore the interrupt
> state.
>
> Fixes: 4ccb45857c2c ("net: stmmac: Fix NAPI poll in TX path when in
> multi-queue")
> Signed-off-by: John Keeping <j...@metanate.com>
> ---
Don't get me wrong, this is so cool that the new lockdep warning is really
helping out finding real bugs, but the patch that adds that warning
(https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?id=cdabce2e3dff7e4bcef73473987618569d178af3)
isn't in 5.4.69-rt39, is it?
