Re: arch/powerpc/sysdev/xive/common.c:1614 xive_debug_show_irq() warn: variable dereferenced before check 'd' (see line 1596)

From: Cédric Le Goater
Date: Wed Mar 03 2021 - 12:54:06 EST

On 2/27/21 4:03 PM, Dan Carpenter wrote:
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head: 3fb6d0e00efc958d01c2f109c8453033a2d96796
> commit: 930914b7d528fc6b0249bffc00564100bcf6ef75 powerpc/xive: Add a debugfs file to dump internal XIVE state
> 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>
>
> New smatch warnings:
> arch/powerpc/sysdev/xive/common.c:1614 xive_debug_show_irq() warn: variable dereferenced before check 'd' (see line 1596)

This should be addressed by patch :

http://patchwork.ozlabs.org/project/linuxppc-dev/patch/20210209161936.377760-5-clg@xxxxxxxx/

> Old smatch warnings:
> arch/powerpc/sysdev/xive/common.c:280 xmon_xive_get_irq_config() warn: variable dereferenced before check 'd' (see line 262)
This one needs a very similar fix which can come as a followup.

Thanks,

C.

> vim +/d +1614 arch/powerpc/sysdev/xive/common.c
>
> 930914b7d528fc Cédric Le Goater 2020-03-06 1594 void xive_debug_show_irq(struct seq_file *m, u32 hw_irq, struct irq_data *d)
> 930914b7d528fc Cédric Le Goater 2020-03-06 1595 {
> 930914b7d528fc Cédric Le Goater 2020-03-06 @1596 struct irq_chip *chip = irq_data_get_irq_chip(d);
> ^
> Dereferenced inside function
>
> 930914b7d528fc Cédric Le Goater 2020-03-06 1597 int rc;
> 930914b7d528fc Cédric Le Goater 2020-03-06 1598 u32 target;
> 930914b7d528fc Cédric Le Goater 2020-03-06 1599 u8 prio;
> 930914b7d528fc Cédric Le Goater 2020-03-06 1600 u32 lirq;
> 930914b7d528fc Cédric Le Goater 2020-03-06 1601
> 930914b7d528fc Cédric Le Goater 2020-03-06 1602 if (!is_xive_irq(chip))
> 930914b7d528fc Cédric Le Goater 2020-03-06 1603 return;
> 930914b7d528fc Cédric Le Goater 2020-03-06 1604
> 930914b7d528fc Cédric Le Goater 2020-03-06 1605 rc = xive_ops->get_irq_config(hw_irq, &target, &prio, &lirq);
> 930914b7d528fc Cédric Le Goater 2020-03-06 1606 if (rc) {
> 930914b7d528fc Cédric Le Goater 2020-03-06 1607 seq_printf(m, "IRQ 0x%08x : no config rc=%d\n", hw_irq, rc);
> 930914b7d528fc Cédric Le Goater 2020-03-06 1608 return;
> 930914b7d528fc Cédric Le Goater 2020-03-06 1609 }
> 930914b7d528fc Cédric Le Goater 2020-03-06 1610
> 930914b7d528fc Cédric Le Goater 2020-03-06 1611 seq_printf(m, "IRQ 0x%08x : target=0x%x prio=%02x lirq=0x%x ",
> 930914b7d528fc Cédric Le Goater 2020-03-06 1612 hw_irq, target, prio, lirq);
> 930914b7d528fc Cédric Le Goater 2020-03-06 1613
> 930914b7d528fc Cédric Le Goater 2020-03-06 @1614 if (d) {
> ^^^^^^^^
> Checked too late.
>
> 930914b7d528fc Cédric Le Goater 2020-03-06 1615 struct xive_irq_data *xd = irq_data_get_irq_handler_data(d);
> 930914b7d528fc Cédric Le Goater 2020-03-06 1616 u64 val = xive_esb_read(xd, XIVE_ESB_GET);
> 930914b7d528fc Cédric Le Goater 2020-03-06 1617
> 930914b7d528fc Cédric Le Goater 2020-03-06 1618 seq_printf(m, "flags=%c%c%c PQ=%c%c",
> 930914b7d528fc Cédric Le Goater 2020-03-06 1619 xd->flags & XIVE_IRQ_FLAG_STORE_EOI ? 'S' : ' ',
> 930914b7d528fc Cédric Le Goater 2020-03-06 1620 xd->flags & XIVE_IRQ_FLAG_LSI ? 'L' : ' ',
> 930914b7d528fc Cédric Le Goater 2020-03-06 1621 xd->flags & XIVE_IRQ_FLAG_H_INT_ESB ? 'H' : ' ',
> 930914b7d528fc Cédric Le Goater 2020-03-06 1622 val & XIVE_ESB_VAL_P ? 'P' : '-',
> 930914b7d528fc Cédric Le Goater 2020-03-06 1623 val & XIVE_ESB_VAL_Q ? 'Q' : '-');
> 930914b7d528fc Cédric Le Goater 2020-03-06 1624 }
> 930914b7d528fc Cédric Le Goater 2020-03-06 1625 seq_puts(m, "\n");
> 930914b7d528fc Cédric Le Goater 2020-03-06 1626 }
>
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