Re: drivers/irqchip/irq-apple-aic.c:941 aic_of_ic_init() error: uninitialized symbol 'off'.

[Marc Zyngier <maz@kernel.org>]

On Mon, 04 Dec 2023 06:41:46 +0000,
Dan Carpenter <dan.carpenter@linaro.org> wrote:
> 
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head:   33cc938e65a98f1d29d0a18403dbbee050dcad9a
> commit: dc97fd6fec009957e81026055fc99a03877ff3b8 irqchip/apple-aic: Dynamically compute register offsets
> config: arm64-randconfig-r081-20231127 (https://download.01.org/0day-ci/archive/20231203/202312032327.J915WcaL-lkp@intel.com/config)
> compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project.git f28c006a5895fc0e329fe15fead81e37457cb1d1)
> reproduce: (https://download.01.org/0day-ci/archive/20231203/202312032327.J915WcaL-lkp@intel.com/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
> | Closes: https://lore.kernel.org/r/202312032327.J915WcaL-lkp@intel.com/
> 
> New smatch warnings:
> drivers/irqchip/irq-apple-aic.c:941 aic_of_ic_init() error: uninitialized symbol 'off'.
> 
> Old smatch warnings:
> drivers/irqchip/irq-apple-aic.c:920 aic_of_ic_init() warn: possible memory leak of 'irqc'
> drivers/irqchip/irq-apple-aic.c:998 aic_of_ic_init() warn: 'regs' from of_iomap() not released on lines: 914,920.
> 
> vim +/off +941 drivers/irqchip/irq-apple-aic.c
> 
> 76cde26394114f Hector Martin 2021-01-21   900  static int __init aic_of_ic_init(struct device_node *node, struct device_node *parent)
> 76cde26394114f Hector Martin 2021-01-21   901  {
> 76cde26394114f Hector Martin 2021-01-21   902  	int i;
> dc97fd6fec0099 Hector Martin 2022-03-10   903  	u32 off;
> 76cde26394114f Hector Martin 2021-01-21   904  	void __iomem *regs;
> 76cde26394114f Hector Martin 2021-01-21   905  	struct aic_irq_chip *irqc;
> 2cf68211664acd Hector Martin 2022-03-10   906  	const struct of_device_id *match;
> 76cde26394114f Hector Martin 2021-01-21   907  
> 76cde26394114f Hector Martin 2021-01-21   908  	regs = of_iomap(node, 0);
> 76cde26394114f Hector Martin 2021-01-21   909  	if (WARN_ON(!regs))
> 76cde26394114f Hector Martin 2021-01-21   910  		return -EIO;
> 76cde26394114f Hector Martin 2021-01-21   911  
> 76cde26394114f Hector Martin 2021-01-21   912  	irqc = kzalloc(sizeof(*irqc), GFP_KERNEL);
> 76cde26394114f Hector Martin 2021-01-21   913  	if (!irqc)
> 76cde26394114f Hector Martin 2021-01-21   914  		return -ENOMEM;
> 76cde26394114f Hector Martin 2021-01-21   915  
> 76cde26394114f Hector Martin 2021-01-21   916  	irqc->base = regs;
> 76cde26394114f Hector Martin 2021-01-21   917  
> 2cf68211664acd Hector Martin 2022-03-10   918  	match = of_match_node(aic_info_match, node);
> 2cf68211664acd Hector Martin 2022-03-10   919  	if (!match)
> 2cf68211664acd Hector Martin 2022-03-10   920  		return -ENODEV;
> 2cf68211664acd Hector Martin 2022-03-10   921  
> 2cf68211664acd Hector Martin 2022-03-10   922  	irqc->info = *(struct aic_info *)match->data;
> 2cf68211664acd Hector Martin 2022-03-10   923  
> 2cf68211664acd Hector Martin 2022-03-10   924  	aic_irqc = irqc;
> 2cf68211664acd Hector Martin 2022-03-10   925  
> dc97fd6fec0099 Hector Martin 2022-03-10   926  	switch (irqc->info.version) {
> dc97fd6fec0099 Hector Martin 2022-03-10   927  	case 1: {
> dc97fd6fec0099 Hector Martin 2022-03-10   928  		u32 info;
> dc97fd6fec0099 Hector Martin 2022-03-10   929  
> 76cde26394114f Hector Martin 2021-01-21   930  		info = aic_ic_read(irqc, AIC_INFO);
> 7c841f5f6fa3f9 Hector Martin 2022-03-10   931  		irqc->nr_irq = FIELD_GET(AIC_INFO_NR_IRQ, info);
> dc97fd6fec0099 Hector Martin 2022-03-10   932  		irqc->max_irq = AIC_MAX_IRQ;
> dc97fd6fec0099 Hector Martin 2022-03-10   933  
> dc97fd6fec0099 Hector Martin 2022-03-10   934  		off = irqc->info.target_cpu;
> dc97fd6fec0099 Hector Martin 2022-03-10   935  		off += sizeof(u32) * irqc->max_irq; /* TARGET_CPU */
> dc97fd6fec0099 Hector Martin 2022-03-10   936  
> dc97fd6fec0099 Hector Martin 2022-03-10   937  		break;
> dc97fd6fec0099 Hector Martin 2022-03-10   938  	}
> 
> not default statement.

This is yet another case of data-driven dependency that smatch cannot
infer easily. info.version is statically set in aic_info_match[]. 1
and 2 are the only values provided by this array, so off is never left
uninitialised.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.