Re: arch/powerpc/sysdev/xive/common.c:279 xmon_xive_get_irq_config() warn: variable dereferenced before check 'd' (see line 261)

[Cédric Le Goater]

On 2/27/21 10:30 AM, Dan Carpenter wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head:   8b83369ddcb3fb9cab5c1088987ce477565bb630
> commit: 97ef275077932c65b1b8ec5022abd737a9fbf3e0 powerpc/xive: Fix xmon support on the PowerNV platform
> config: powerpc64-randconfig-m031-20210226 (attached as .config)
> compiler: powerpc64-linux-gcc (GCC) 9.3.0
> 
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> 
> smatch warnings:
> arch/powerpc/sysdev/xive/common.c:279 xmon_xive_get_irq_config() warn: variable dereferenced before check 'd' (see line 261)

Yes. That's ugly :/

I would prefer to address this issue after the cleanup provided
by the patchset adding an IRQ domain for IPIs.

  http://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=228762

Most of the mess comes from the XIVE IPI HW IRQ number which
hijacks IRQ number 0. It should be easier after this is fixed.

Thanks,

C. 

> vim +/d +279 arch/powerpc/sysdev/xive/common.c
> 
> 5896163f7f91c05 Cédric Le Goater 2019-09-10  259  int xmon_xive_get_irq_config(u32 hw_irq, struct irq_data *d)
> b4868ff55d082bc Cédric Le Goater 2019-08-14  260  {
> 97ef275077932c6 Cédric Le Goater 2020-03-06 @261  	struct irq_chip *chip = irq_data_get_irq_chip(d);
>                                                                                                       ^
> Dereferenced inside function
> 
> 5896163f7f91c05 Cédric Le Goater 2019-09-10  262  	int rc;
> 5896163f7f91c05 Cédric Le Goater 2019-09-10  263  	u32 target;
> 5896163f7f91c05 Cédric Le Goater 2019-09-10  264  	u8 prio;
> 5896163f7f91c05 Cédric Le Goater 2019-09-10  265  	u32 lirq;
> 5896163f7f91c05 Cédric Le Goater 2019-09-10  266  
> 97ef275077932c6 Cédric Le Goater 2020-03-06  267  	if (!is_xive_irq(chip))
> 97ef275077932c6 Cédric Le Goater 2020-03-06  268  		return -EINVAL;
> 97ef275077932c6 Cédric Le Goater 2020-03-06  269  
> 5896163f7f91c05 Cédric Le Goater 2019-09-10  270  	rc = xive_ops->get_irq_config(hw_irq, &target, &prio, &lirq);
> 5896163f7f91c05 Cédric Le Goater 2019-09-10  271  	if (rc) {
> 5896163f7f91c05 Cédric Le Goater 2019-09-10  272  		xmon_printf("IRQ 0x%08x : no config rc=%d\n", hw_irq, rc);
> 5896163f7f91c05 Cédric Le Goater 2019-09-10  273  		return rc;
> 5896163f7f91c05 Cédric Le Goater 2019-09-10  274  	}
> 5896163f7f91c05 Cédric Le Goater 2019-09-10  275  
> 5896163f7f91c05 Cédric Le Goater 2019-09-10  276  	xmon_printf("IRQ 0x%08x : target=0x%x prio=%02x lirq=0x%x ",
> 5896163f7f91c05 Cédric Le Goater 2019-09-10  277  		    hw_irq, target, prio, lirq);
> 5896163f7f91c05 Cédric Le Goater 2019-09-10  278  
> 5896163f7f91c05 Cédric Le Goater 2019-09-10 @279  	if (d) {
>                                                         ^^^^^^
> Checked too late
> 
> 5896163f7f91c05 Cédric Le Goater 2019-09-10  280  		struct xive_irq_data *xd = irq_data_get_irq_handler_data(d);
> 5896163f7f91c05 Cédric Le Goater 2019-09-10  281  		u64 val = xive_esb_read(xd, XIVE_ESB_GET);
> 5896163f7f91c05 Cédric Le Goater 2019-09-10  282  
> 5896163f7f91c05 Cédric Le Goater 2019-09-10  283  		xmon_printf("PQ=%c%c",
> 5896163f7f91c05 Cédric Le Goater 2019-09-10  284  			    val & XIVE_ESB_VAL_P ? 'P' : '-',
> 5896163f7f91c05 Cédric Le Goater 2019-09-10  285  			    val & XIVE_ESB_VAL_Q ? 'Q' : '-');
> 5896163f7f91c05 Cédric Le Goater 2019-09-10  286  	}
> 5896163f7f91c05 Cédric Le Goater 2019-09-10  287  
> 5896163f7f91c05 Cédric Le Goater 2019-09-10  288  	xmon_printf("\n");
> 5896163f7f91c05 Cédric Le Goater 2019-09-10  289  	return 0;
> b4868ff55d082bc Cédric Le Goater 2019-08-14  290  }
> 
> ---
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