linux-kernel - Re: [PATCH] MIPS: Remove no-op cast in show

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Date:   Mon, 2 Jul 2018 23:00:36 +0200 (CEST)
From:   Julia Lawall <julia.lawall@...6.fr>
To:     Ralf Baechle <ralf@...ux-mips.org>
cc:     Paul Burton <paul.burton@...s.com>, linux-mips@...ux-mips.org,
        James Hogan <jhogan@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] MIPS: Remove no-op cast in show_regs()



On Mon, 2 Jul 2018, Ralf Baechle wrote:

> On Fri, Jun 22, 2018 at 11:07:03AM -0700, Paul Burton wrote:
>
> > In show_regs() we have a regs argument of type struct pt_regs *, and we
> > explicitly cast it to that same type as part of calling __show_regs().
> >
> > Casting regs to the same type that it is declared as does nothing at
> > all, so remove the useless cast.
>
> Good catch but there's no dump_stack() in v4.18-rc3 so this doesn't apply.
> That's trivial to patch up but since pointless casts are one of my pet
> peeve I used a semantic patch from a dark local repository to hunt down a
> few more.
>
> @identitycast@
> type T;
> T *A;
> @@
> -	(T *) A
> +	A
>
> Julia, I guess this isn't bulletproof but maybe something similar should
> be considered for scripts/coccinelle?

Thanks for the suggestion.  I will try to put together something.  From
the examples, it looks like - (T *)(A) could be better.  With that
Coccinelle will also match cases with no parentheses.

julia

>
>   Ralf
>
> Signed-off-by: Ralf Baechle <ralf@...ux-mips.org>
>
>  arch/mips/kernel/relocate.c           |  2 +-
>  arch/mips/kernel/traps.c              |  2 +-
>  arch/mips/loongson64/loongson-3/smp.c | 10 +++++-----
>  arch/mips/pmcs-msp71xx/msp_usb.c      |  4 ++--
>  arch/mips/sgi-ip22/ip28-berr.c        |  2 +-
>  5 files changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/arch/mips/kernel/relocate.c b/arch/mips/kernel/relocate.c
> index cbf4cc0b0b6c..ae7d9cf2c849 100644
> --- a/arch/mips/kernel/relocate.c
> +++ b/arch/mips/kernel/relocate.c
> @@ -146,7 +146,7 @@ int __init do_relocations(void *kbase_old, void *kbase_new, long offset)
>  			break;
>
>  		type = (*r >> 24) & 0xff;
> -		loc_orig = (void *)(kbase_old + ((*r & 0x00ffffff) << 2));
> +		loc_orig = (kbase_old + ((*r & 0x00ffffff) << 2));
>  		loc_new = RELOCATED(loc_orig);
>
>  		if (reloc_handlers_rel[type] == NULL) {
> diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
> index d67fa74622ee..2935aa608d2f 100644
> --- a/arch/mips/kernel/traps.c
> +++ b/arch/mips/kernel/traps.c
> @@ -350,7 +350,7 @@ static void __show_regs(const struct pt_regs *regs)
>   */
>  void show_regs(struct pt_regs *regs)
>  {
> -	__show_regs((struct pt_regs *)regs);
> +	__show_regs(regs);
>  }
>
>  void show_registers(struct pt_regs *regs)
> diff --git a/arch/mips/loongson64/loongson-3/smp.c b/arch/mips/loongson64/loongson-3/smp.c
> index 8501109bb0f0..e231c2cb4a64 100644
> --- a/arch/mips/loongson64/loongson-3/smp.c
> +++ b/arch/mips/loongson64/loongson-3/smp.c
> @@ -349,7 +349,7 @@ static void loongson3_smp_finish(void)
>  	write_c0_compare(read_c0_count() + mips_hpt_frequency/HZ);
>  	local_irq_enable();
>  	loongson3_ipi_write64(0,
> -			(void *)(ipi_mailbox_buf[cpu_logical_map(cpu)]+0x0));
> +			(ipi_mailbox_buf[cpu_logical_map(cpu)] + 0x0));
>  	pr_info("CPU#%d finished, CP0_ST=%x\n",
>  			smp_processor_id(), read_c0_status());
>  }
> @@ -416,13 +416,13 @@ static int loongson3_boot_secondary(int cpu, struct task_struct *idle)
>  			cpu, startargs[0], startargs[1], startargs[2]);
>
>  	loongson3_ipi_write64(startargs[3],
> -			(void *)(ipi_mailbox_buf[cpu_logical_map(cpu)]+0x18));
> +			(ipi_mailbox_buf[cpu_logical_map(cpu)] + 0x18));
>  	loongson3_ipi_write64(startargs[2],
> -			(void *)(ipi_mailbox_buf[cpu_logical_map(cpu)]+0x10));
> +			(ipi_mailbox_buf[cpu_logical_map(cpu)] + 0x10));
>  	loongson3_ipi_write64(startargs[1],
> -			(void *)(ipi_mailbox_buf[cpu_logical_map(cpu)]+0x8));
> +			(ipi_mailbox_buf[cpu_logical_map(cpu)] + 0x8));
>  	loongson3_ipi_write64(startargs[0],
> -			(void *)(ipi_mailbox_buf[cpu_logical_map(cpu)]+0x0));
> +			(ipi_mailbox_buf[cpu_logical_map(cpu)] + 0x0));
>  	return 0;
>  }
>
> diff --git a/arch/mips/pmcs-msp71xx/msp_usb.c b/arch/mips/pmcs-msp71xx/msp_usb.c
> index c87c5f810cd1..d38ac70b5a2e 100644
> --- a/arch/mips/pmcs-msp71xx/msp_usb.c
> +++ b/arch/mips/pmcs-msp71xx/msp_usb.c
> @@ -133,13 +133,13 @@ static int __init msp_usb_setup(void)
>  	 * "D" for device-mode.	 If it works for Ethernet, why not USB...
>  	 *  -- hammtrev, 2007/03/22
>  	 */
> -	snprintf((char *)&envstr[0], sizeof(envstr), "usbmode");
> +	snprintf(&envstr[0], sizeof(envstr), "usbmode");
>
>  	/* set default host mode */
>  	val = 1;
>
>  	/* get environment string */
> -	strp = prom_getenv((char *)&envstr[0]);
> +	strp = prom_getenv(&envstr[0]);
>  	if (strp) {
>  		/* compare string */
>  		if (!strcmp(strp, "device"))
> diff --git a/arch/mips/sgi-ip22/ip28-berr.c b/arch/mips/sgi-ip22/ip28-berr.c
> index 2ed8e4990b7a..082541d33161 100644
> --- a/arch/mips/sgi-ip22/ip28-berr.c
> +++ b/arch/mips/sgi-ip22/ip28-berr.c
> @@ -464,7 +464,7 @@ void ip22_be_interrupt(int irq)
>  		die_if_kernel("Oops", regs);
>  		force_sig(SIGBUS, current);
>  	} else if (debug_be_interrupt)
> -		show_regs((struct pt_regs *)regs);
> +		show_regs(regs);
>  }
>
>  static int ip28_be_handler(struct pt_regs *regs, int is_fixup)
>