linux-kernel - Re: [PATCH 1/2] habanalabs: Replace dma-fence mechanism with completions

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Date:   Fri, 31 Jul 2020 03:33:19 +0800
From:   kernel test robot <lkp@...el.com>
To:     Oded Gabbay <oded.gabbay@...il.com>, linux-kernel@...r.kernel.org,
        SW_Drivers@...ana.ai
Cc:     kbuild-all@...ts.01.org, Ofir Bitton <obitton@...ana.ai>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Daniel Vetter <daniel.vetter@...ll.ch>
Subject: Re: [PATCH 1/2] habanalabs: Replace dma-fence mechanism with
 completions

Hi Oded,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on char-misc/char-misc-testing]
[also build test WARNING on next-20200730]
[cannot apply to linux/master linus/master v5.8-rc7]
[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]

url:    https://github.com/0day-ci/linux/commits/Oded-Gabbay/habanalabs-Replace-dma-fence-mechanism-with-completions/20200730-211536
base:   https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git 22362aa30bad6f03b5bcbbeee3cdc61950d40086
config: riscv-allyesconfig (attached as .config)
compiler: riscv64-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=riscv 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@...el.com>

All warnings (new ones prefixed by >>):

>> drivers/misc/habanalabs/common/command_submission.c:41:6: warning: no previous prototype for 'hl_fence_release' [-Wmissing-prototypes]
      41 | void hl_fence_release(struct kref *kref)
         |      ^~~~~~~~~~~~~~~~
>> drivers/misc/habanalabs/common/command_submission.c:101:6: warning: no previous prototype for 'hl_fence_init' [-Wmissing-prototypes]
     101 | void hl_fence_init(struct hl_fence *fence)
         |      ^~~~~~~~~~~~~

vim +/hl_fence_release +41 drivers/misc/habanalabs/common/command_submission.c

    40	
  > 41	void hl_fence_release(struct kref *kref)
    42	{
    43		struct hl_fence *fence =
    44			container_of(kref, struct hl_fence, refcount);
    45		struct hl_cs_compl *hl_cs_cmpl =
    46			container_of(fence, struct hl_cs_compl, base_fence);
    47		struct hl_device *hdev = hl_cs_cmpl->hdev;
    48	
    49		/* EBUSY means the CS was never submitted and hence we don't have
    50		 * an attached hw_sob object that we should handle here
    51		 */
    52		if (fence->error == -EBUSY)
    53			goto free;
    54	
    55		if ((hl_cs_cmpl->type == CS_TYPE_SIGNAL) ||
    56				(hl_cs_cmpl->type == CS_TYPE_WAIT)) {
    57	
    58			dev_dbg(hdev->dev,
    59				"CS 0x%llx type %d finished, sob_id: %d, sob_val: 0x%x\n",
    60				hl_cs_cmpl->cs_seq,
    61				hl_cs_cmpl->type,
    62				hl_cs_cmpl->hw_sob->sob_id,
    63				hl_cs_cmpl->sob_val);
    64	
    65			/*
    66			 * A signal CS can get completion while the corresponding wait
    67			 * for signal CS is on its way to the PQ. The wait for signal CS
    68			 * will get stuck if the signal CS incremented the SOB to its
    69			 * max value and there are no pending (submitted) waits on this
    70			 * SOB.
    71			 * We do the following to void this situation:
    72			 * 1. The wait for signal CS must get a ref for the signal CS as
    73			 *    soon as possible in cs_ioctl_signal_wait() and put it
    74			 *    before being submitted to the PQ but after it incremented
    75			 *    the SOB refcnt in init_signal_wait_cs().
    76			 * 2. Signal/Wait for signal CS will decrement the SOB refcnt
    77			 *    here.
    78			 * These two measures guarantee that the wait for signal CS will
    79			 * reset the SOB upon completion rather than the signal CS and
    80			 * hence the above scenario is avoided.
    81			 */
    82			kref_put(&hl_cs_cmpl->hw_sob->kref, hl_sob_reset);
    83		}
    84	
    85	free:
    86		kfree_rcu(hl_cs_cmpl, base_fence.rcu);
    87	}
    88	
    89	void hl_fence_put(struct hl_fence *fence)
    90	{
    91		if (fence)
    92			kref_put(&fence->refcount, hl_fence_release);
    93	}
    94	
    95	void hl_fence_get(struct hl_fence *fence)
    96	{
    97		if (fence)
    98			kref_get(&fence->refcount);
    99	}
   100	
 > 101	void hl_fence_init(struct hl_fence *fence)
   102	{
   103		kref_init(&fence->refcount);
   104		fence->error = 0;
   105		init_completion(&fence->completion);
   106	}
   107	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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