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

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Date:   Sat, 27 Feb 2021 18:03:25 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     kbuild@...ts.01.org,
        Cédric Le Goater <clg@...d.org>
Cc:     lkp@...el.com, kbuild-all@...ts.01.org,
        linux-kernel@...r.kernel.org, Michael Ellerman <mpe@...erman.id.au>
Subject: arch/powerpc/sysdev/xive/common.c:1614 xive_debug_show_irq() warn:
 variable dereferenced before check 'd' (see line 1596)

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@...el.com>
Reported-by: Dan Carpenter <dan.carpenter@...cle.com>

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

Old smatch warnings:
arch/powerpc/sysdev/xive/common.c:280 xmon_xive_get_irq_config() warn: variable dereferenced before check 'd' (see line 262)

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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