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Message-ID: <202512061812.Xbqmd2Gn-lkp@intel.com>
Date: Sat, 6 Dec 2025 19:03:50 +0800
From: kernel test robot <lkp@...el.com>
To: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Cc: oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org,
	Bjorn Helgaas <helgaas@...nel.org>,
	Manivannan Sadhasivam <mani@...nel.org>
Subject: include/linux/bitmap.h:820:13: warning: 'bitmap' is used
 uninitialized in this function

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   416f99c3b16f582a3fc6d64a1f77f39d94b76de5
commit: 7ef502fb35b283e0f85ed7b34e2d963343981a8c PCI: Add Renesas RZ/G3S host controller driver
date:   11 days ago
config: sparc64-randconfig-r133-20251206 (https://download.01.org/0day-ci/archive/20251206/202512061812.Xbqmd2Gn-lkp@intel.com/config)
compiler: sparc64-linux-gcc (GCC) 10.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251206/202512061812.Xbqmd2Gn-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@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202512061812.Xbqmd2Gn-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from drivers/pci/controller/pcie-rzg3s-host.c:13:
   drivers/pci/controller/pcie-rzg3s-host.c: In function 'rzg3s_pcie_msi_irq.part.0':
>> include/linux/bitmap.h:820:13: warning: 'bitmap' is used uninitialized in this function [-Wuninitialized]
     820 |  map[index] &= (fit ? (~(mask << offset)) : ~BITMAP_FIRST_WORD_MASK(start));
         |             ^~
   In file included from include/linux/kasan-checks.h:5,
                    from include/asm-generic/rwonce.h:26,
                    from ./arch/sparc/include/generated/asm/rwonce.h:1,
                    from include/linux/compiler.h:382,
                    from include/linux/build_bug.h:5,
                    from include/linux/bitfield.h:10,
                    from drivers/pci/controller/pcie-rzg3s-host.c:12:
   drivers/pci/controller/pcie-rzg3s-host.c:482:17: note: 'bitmap' was declared here
     482 |  DECLARE_BITMAP(bitmap, RZG3S_PCI_MSI_INT_NR);
         |                 ^~~~~~
   include/linux/types.h:11:16: note: in definition of macro 'DECLARE_BITMAP'
      11 |  unsigned long name[BITS_TO_LONGS(bits)]
         |                ^~~~


vim +/bitmap +820 include/linux/bitmap.h

63c15822b8dd02 Syed Nayyar Waris 2024-03-27  784  
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  785  /**
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  786   * bitmap_write - write n-bit value within a memory region
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  787   * @map: address to the bitmap memory region
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  788   * @value: value to write, clamped to nbits
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  789   * @start: bit offset of the n-bit value
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  790   * @nbits: size of value in bits, nonzero, up to BITS_PER_LONG.
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  791   *
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  792   * bitmap_write() behaves as-if implemented as @nbits calls of __assign_bit(),
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  793   * i.e. bits beyond @nbits are ignored:
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  794   *
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  795   *   for (bit = 0; bit < nbits; bit++)
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  796   *           __assign_bit(start + bit, bitmap, val & BIT(bit));
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  797   *
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  798   * For @nbits == 0 and @nbits > BITS_PER_LONG no writes are performed.
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  799   */
ed8cd2b3bd9f07 Yury Norov        2024-07-18  800  static __always_inline
ed8cd2b3bd9f07 Yury Norov        2024-07-18  801  void bitmap_write(unsigned long *map, unsigned long value,
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  802  		  unsigned long start, unsigned long nbits)
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  803  {
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  804  	size_t index;
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  805  	unsigned long offset;
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  806  	unsigned long space;
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  807  	unsigned long mask;
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  808  	bool fit;
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  809  
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  810  	if (unlikely(!nbits || nbits > BITS_PER_LONG))
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  811  		return;
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  812  
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  813  	mask = BITMAP_LAST_WORD_MASK(nbits);
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  814  	value &= mask;
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  815  	offset = start % BITS_PER_LONG;
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  816  	space = BITS_PER_LONG - offset;
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  817  	fit = space >= nbits;
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  818  	index = BIT_WORD(start);
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  819  
63c15822b8dd02 Syed Nayyar Waris 2024-03-27 @820  	map[index] &= (fit ? (~(mask << offset)) : ~BITMAP_FIRST_WORD_MASK(start));
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  821  	map[index] |= value << offset;
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  822  	if (fit)
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  823  		return;
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  824  
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  825  	map[index + 1] &= BITMAP_FIRST_WORD_MASK(start + nbits);
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  826  	map[index + 1] |= (value >> space);
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  827  }
63c15822b8dd02 Syed Nayyar Waris 2024-03-27  828  

:::::: The code at line 820 was first introduced by commit
:::::: 63c15822b8dd02a2423cfd92232245ace3f7a11b lib/bitmap: add bitmap_{read,write}()

:::::: TO: Syed Nayyar Waris <syednwaris@...il.com>
:::::: CC: David S. Miller <davem@...emloft.net>

-- 
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https://github.com/intel/lkp-tests/wiki

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