Re: [PATCH 2/2] net: mana: Allow MANA driver to allocate PCI vector dynamically

[kernel test robot <lkp@intel.com>]

Hi Shradha,

kernel test robot noticed the following build warnings:

[auto build test WARNING on pci/next]
[also build test WARNING on pci/for-linus linus/master v6.15-rc5 next-20250507]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Shradha-Gupta/PCI-hv-enable-pci_hyperv-to-allow-dynamic-vector-allocation/20250416-233828
base:   https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git next
patch link:    https://lore.kernel.org/r/1744817781-3243-1-git-send-email-shradhagupta%40linux.microsoft.com
patch subject: [PATCH 2/2] net: mana: Allow MANA driver to allocate PCI vector dynamically
config: x86_64-allyesconfig (https://download.01.org/0day-ci/archive/20250508/202505080049.7AvfzOGc-lkp@intel.com/config)
compiler: clang version 20.1.2 (https://github.com/llvm/llvm-project 58df0ef89dd64126512e4ee27b4ac3fd8ddf6247)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250508/202505080049.7AvfzOGc-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>
| Closes: https://lore.kernel.org/oe-kbuild-all/202505080049.7AvfzOGc-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/net/ethernet/microsoft/mana/gdma_main.c:500:2: warning: variable 'gic' is used uninitialized whenever 'for' loop exits because its condition is false [-Wsometimes-uninitialized]
     500 |         list_for_each(pos, &gc->irq_contexts) {
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/list.h:687:27: note: expanded from macro 'list_for_each'
     687 |         for (pos = (head)->next; !list_is_head(pos, (head)); pos = pos->next)
         |                                  ^~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/net/ethernet/microsoft/mana/gdma_main.c:510:7: note: uninitialized use occurs here
     510 |         if (!gic)
         |              ^~~
   drivers/net/ethernet/microsoft/mana/gdma_main.c:500:2: note: remove the condition if it is always true
     500 |         list_for_each(pos, &gc->irq_contexts) {
         |         ^
   include/linux/list.h:687:27: note: expanded from macro 'list_for_each'
     687 |         for (pos = (head)->next; !list_is_head(pos, (head)); pos = pos->next)
         |                                  ^
   drivers/net/ethernet/microsoft/mana/gdma_main.c:475:30: note: initialize the variable 'gic' to silence this warning
     475 |         struct gdma_irq_context *gic;
         |                                     ^
         |                                      = NULL
   drivers/net/ethernet/microsoft/mana/gdma_main.c:541:2: warning: variable 'gic' is used uninitialized whenever 'for' loop exits because its condition is false [-Wsometimes-uninitialized]
     541 |         list_for_each(pos, &gc->irq_contexts) {
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/list.h:687:27: note: expanded from macro 'list_for_each'
     687 |         for (pos = (head)->next; !list_is_head(pos, (head)); pos = pos->next)
         |                                  ^~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/net/ethernet/microsoft/mana/gdma_main.c:551:7: note: uninitialized use occurs here
     551 |         if (!gic)
         |              ^~~
   drivers/net/ethernet/microsoft/mana/gdma_main.c:541:2: note: remove the condition if it is always true
     541 |         list_for_each(pos, &gc->irq_contexts) {
         |         ^
   include/linux/list.h:687:27: note: expanded from macro 'list_for_each'
     687 |         for (pos = (head)->next; !list_is_head(pos, (head)); pos = pos->next)
         |                                  ^
   drivers/net/ethernet/microsoft/mana/gdma_main.c:523:30: note: initialize the variable 'gic' to silence this warning
     523 |         struct gdma_irq_context *gic;
         |                                     ^
         |                                      = NULL
   2 warnings generated.


vim +500 drivers/net/ethernet/microsoft/mana/gdma_main.c

   470	
   471	static int mana_gd_register_irq(struct gdma_queue *queue,
   472					const struct gdma_queue_spec *spec)
   473	{
   474		struct gdma_dev *gd = queue->gdma_dev;
   475		struct gdma_irq_context *gic;
   476		struct gdma_context *gc;
   477		unsigned int msi_index;
   478		struct list_head *pos;
   479		unsigned long flags, flag_irq;
   480		struct device *dev;
   481		int err = 0, count;
   482	
   483		gc = gd->gdma_context;
   484		dev = gc->dev;
   485		msi_index = spec->eq.msix_index;
   486	
   487		if (msi_index >= gc->num_msix_usable) {
   488			err = -ENOSPC;
   489			dev_err(dev, "Register IRQ err:%d, msi:%u nMSI:%u",
   490				err, msi_index, gc->num_msix_usable);
   491	
   492			return err;
   493		}
   494	
   495		queue->eq.msix_index = msi_index;
   496	
   497		/* get the msi_index value from the list*/
   498		count = 0;
   499		spin_lock_irqsave(&gc->irq_ctxs_lock, flag_irq);
 > 500		list_for_each(pos, &gc->irq_contexts) {
   501			if (count == msi_index) {
   502				gic = list_entry(pos, struct gdma_irq_context, gic_list);
   503				break;
   504			}
   505	
   506			count++;
   507		}
   508		spin_unlock_irqrestore(&gc->irq_ctxs_lock, flag_irq);
   509	
   510		if (!gic)
   511			return -1;
   512	
   513		spin_lock_irqsave(&gic->lock, flags);
   514		list_add_rcu(&queue->entry, &gic->eq_list);
   515		spin_unlock_irqrestore(&gic->lock, flags);
   516	
   517		return 0;
   518	}
   519	

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