Re: [PATCH rtw-next v2] wifi: rtlwifi: rtl8723be: Remove unnecessary irq save/restore in hw_init()

[Ping-Ke Shih]

William Hansen-Baird <william.hansen.baird@xxxxxxxxx> wrote:

> rtl8723be hw_init() calls local_save_flags(flags) followed by
> local_irq_enable(). Later, local_irq_restore(flags) is called.
> 
> This causes warnings from Lockdep on boot and modprobe,
> as local_irq_restore(flags) should only be called while irqs are disabled.
> The warning was introduced to detect this class of bug in [1].
> 
> With testing I found that all paths which call hw_init() have irqs
> already enabled for rtl8723be.
> 
> Furthermore, the calls were originally added for the rtl8192ce
> in commit f78bccd79ba3 ("rtlwifi: rtl8192ce: Fix too long disable of IRQs")
> before later being added to most other rtlwifi drivers.
> 
> Commit d3feae41a347 ("rtlwifi: Update power-save routines for 062814 driver")
> then replaces the call to spin_lock_irqsave() before hw_init(),
> and thus the codepath which caused irqs to be disabled in hw_init and
> prompted the original commit has been removed.
> 
> The same irq save/restore pattern is also present in the hw_init() of
> rtl8192ce, rtl8723ae, rtl8188ee, rtl8192se and rtl8192cu,
> however I don't have the hardware to test them,
> so I did not include them in my changes.
> 
> Tested on a Razer Blade 14 2017.
> 
> Example of output from Lockdep prior to fix:
> 
> raw_local_irq_restore() called with IRQs enabled
> 
> ...
> 
> Call Trace:
> <TASK>
> rtl8723be_hw_init+0x5992/0x7220 [rtl8723be]
> ? static_obj+0x61/0xa0
> rtl_pci_start+0x222/0x5c0 [rtl_pci]
> rtl_op_start+0x128/0x1a0 [rtlwifi]
> ? __kasan_check_read+0x11/0x20
> drv_start+0x16c/0x550 [mac80211]
> 
> ...
> 
> irq event stamp: 887679
> hardirqs last  enabled at (887689): [<ffffffff96511170>] __up_console_sem+0x90/0xa0
> hardirqs last disabled at (887698): [<ffffffff96511155>] __up_console_sem+0x75/0xa0
> softirqs last  enabled at (887670): [<ffffffff962f4675>] __irq_exit_rcu+0x175/0x2f0
> softirqs last disabled at (887649): [<ffffffff962f4675>] __irq_exit_rcu+0x175/0x2f0
> ---[ end trace 0000000000000000 ]---
> 
> [1] https://lore.kernel.org/all/20210111153707.10071-1-mark.rutland@xxxxxxx/
> 
> Signed-off-by: William Hansen-Baird <william.hansen.baird@xxxxxxxxx>
> Acked-by: Ping-Ke Shih <pkshih@xxxxxxxxxxx>

1 patch(es) applied to rtw-next branch of rtw.git, thanks.

1b4cd55626b6 wifi: rtlwifi: rtl8723be: Remove unnecessary irq save/restore in hw_init()

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https://github.com/pkshih/rtw.git