linux-kernel - Re: [PATCH net-next v22 1/2] mailbox/pcc: support mailbox management of the shared buffer

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Message-ID: <202507111440.1zQdhxpr-lkp@intel.com>
Date: Fri, 11 Jul 2025 14:51:25 +0800
From: kernel test robot <lkp@...el.com>
To: admiyo@...amperecomputing.com, Sudeep Holla <sudeep.holla@....com>,
	Jassi Brar <jassisinghbrar@...il.com>,
	Robert Moore <robert.moore@...el.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Len Brown <lenb@...nel.org>
Cc: llvm@...ts.linux.dev, oe-kbuild-all@...ts.linux.dev,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	Jeremy Kerr <jk@...econstruct.com.au>,
	Matt Johnston <matt@...econstruct.com.au>,
	"David S . Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Jonathan Cameron <Jonathan.Cameron@...wei.com>,
	Huisong Li <lihuisong@...wei.com>
Subject: Re: [PATCH net-next v22 1/2] mailbox/pcc: support mailbox management
 of the shared buffer

Hi,

kernel test robot noticed the following build warnings:

[auto build test WARNING on net-next/main]

url:    https://github.com/intel-lab-lkp/linux/commits/admiyo-os-amperecomputing-com/mailbox-pcc-support-mailbox-management-of-the-shared-buffer/20250711-031525
base:   net-next/main
patch link:    https://lore.kernel.org/r/20250710191209.737167-2-admiyo%40os.amperecomputing.com
patch subject: [PATCH net-next v22 1/2] mailbox/pcc: support mailbox management of the shared buffer
config: i386-randconfig-014-20250711 (https://download.01.org/0day-ci/archive/20250711/202507111440.1zQdhxpr-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250711/202507111440.1zQdhxpr-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/202507111440.1zQdhxpr-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/mailbox/pcc.c:496:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
     496 |         if (pchan->chan.rx_alloc)
         |             ^~~~~~~~~~~~~~~~~~~~
   drivers/mailbox/pcc.c:498:6: note: uninitialized use occurs here
     498 |         if (ret)
         |             ^~~
   drivers/mailbox/pcc.c:496:2: note: remove the 'if' if its condition is always true
     496 |         if (pchan->chan.rx_alloc)
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~
     497 |                 ret = pcc_write_to_buffer(chan, data);
   drivers/mailbox/pcc.c:492:9: note: initialize the variable 'ret' to silence this warning
     492 |         int ret;
         |                ^
         |                 = 0
   1 warning generated.


vim +496 drivers/mailbox/pcc.c

   476	
   477	
   478	/**
   479	 * pcc_send_data - Called from Mailbox Controller code. Used
   480	 *		here only to ring the channel doorbell. The PCC client
   481	 *		specific read/write is done in the client driver in
   482	 *		order to maintain atomicity over PCC channel once
   483	 *		OS has control over it. See above for flow of operations.
   484	 * @chan: Pointer to Mailbox channel over which to send data.
   485	 * @data: Client specific data written over channel. Used here
   486	 *		only for debug after PCC transaction completes.
   487	 *
   488	 * Return: Err if something failed else 0 for success.
   489	 */
   490	static int pcc_send_data(struct mbox_chan *chan, void *data)
   491	{
   492		int ret;
   493		struct pcc_chan_info *pchan = chan->con_priv;
   494		struct acpi_pcct_ext_pcc_shared_memory __iomem *pcc_hdr;
   495	
 > 496		if (pchan->chan.rx_alloc)
   497			ret = pcc_write_to_buffer(chan, data);
   498		if (ret)
   499			return ret;
   500	
   501		ret = pcc_chan_reg_read_modify_write(&pchan->cmd_update);
   502		if (ret)
   503			return ret;
   504	
   505		pcc_hdr = pchan->chan.shmem;
   506		if (ioread32(&pcc_hdr->flags) & PCC_CMD_COMPLETION_NOTIFY)
   507			pchan->chan.irq_ack = true;
   508	
   509		ret = pcc_chan_reg_read_modify_write(&pchan->db);
   510	
   511		if (!ret && pchan->plat_irq > 0)
   512			pchan->chan_in_use = true;
   513	
   514		return ret;
   515	}
   516	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki