Re: [PATCH 1/2] mailbox: Add power_get/power_put API to mbox_chan_ops

[Dan Carpenter <dan.carpenter@linaro.org>]

Hi Jason-JH.Lin,

kernel test robot noticed the following build warnings:

https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Jason-JH-Lin/mailbox-Add-power_get-power_put-API-to-mbox_chan_ops/20240614-120412
base:   linus/master
patch link:    https://lore.kernel.org/r/20240614040133.24967-2-jason-jh.lin%40mediatek.com
patch subject: [PATCH 1/2] mailbox: Add power_get/power_put API to mbox_chan_ops
config: x86_64-randconfig-161-20240615 (https://download.01.org/0day-ci/archive/20240615/202406151520.TDnOFFbV-lkp@intel.com/config)
compiler: gcc-13 (Ubuntu 13.2.0-4ubuntu3) 13.2.0

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>
| Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
| Closes: https://lore.kernel.org/r/202406151520.TDnOFFbV-lkp@intel.com/

smatch warnings:
drivers/mailbox/mailbox.c:485 mbox_request_channel() error: 'chan' dereferencing possible ERR_PTR()

vim +/chan +485 drivers/mailbox/mailbox.c

2b6d83e2b8b7de Jassi Brar      2014-06-12  444  struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index)
2b6d83e2b8b7de Jassi Brar      2014-06-12  445  {
2b6d83e2b8b7de Jassi Brar      2014-06-12  446  	struct device *dev = cl->dev;
2b6d83e2b8b7de Jassi Brar      2014-06-12  447  	struct mbox_controller *mbox;
2b6d83e2b8b7de Jassi Brar      2014-06-12  448  	struct of_phandle_args spec;
2b6d83e2b8b7de Jassi Brar      2014-06-12  449  	struct mbox_chan *chan;
2b6d83e2b8b7de Jassi Brar      2014-06-12  450  	int ret;
2b6d83e2b8b7de Jassi Brar      2014-06-12  451  
2b6d83e2b8b7de Jassi Brar      2014-06-12  452  	if (!dev || !dev->of_node) {
2b6d83e2b8b7de Jassi Brar      2014-06-12  453  		pr_debug("%s: No owner device node\n", __func__);
2b6d83e2b8b7de Jassi Brar      2014-06-12  454  		return ERR_PTR(-ENODEV);
2b6d83e2b8b7de Jassi Brar      2014-06-12  455  	}
2b6d83e2b8b7de Jassi Brar      2014-06-12  456  
2b6d83e2b8b7de Jassi Brar      2014-06-12  457  	mutex_lock(&con_mutex);
2b6d83e2b8b7de Jassi Brar      2014-06-12  458  
2b6d83e2b8b7de Jassi Brar      2014-06-12  459  	if (of_parse_phandle_with_args(dev->of_node, "mboxes",
2b6d83e2b8b7de Jassi Brar      2014-06-12  460  				       "#mbox-cells", index, &spec)) {
b6d83e2b8b7de Jassi Brar      2014-06-12  461  		dev_dbg(dev, "%s: can't parse \"mboxes\" property\n", __func__);
2b6d83e2b8b7de Jassi Brar      2014-06-12  462  		mutex_unlock(&con_mutex);
2b6d83e2b8b7de Jassi Brar      2014-06-12  463  		return ERR_PTR(-ENODEV);
2b6d83e2b8b7de Jassi Brar      2014-06-12  464  	}
2b6d83e2b8b7de Jassi Brar      2014-06-12  465  
2d805fc1c6b2ec Benson Leung    2015-05-04  466  	chan = ERR_PTR(-EPROBE_DEFER);
2b6d83e2b8b7de Jassi Brar      2014-06-12  467  	list_for_each_entry(mbox, &mbox_cons, node)
2b6d83e2b8b7de Jassi Brar      2014-06-12  468  		if (mbox->dev->of_node == spec.np) {
2b6d83e2b8b7de Jassi Brar      2014-06-12  469  			chan = mbox->of_xlate(mbox, &spec);
8ed82e23875e60 Mikko Perttunen 2018-11-28  470  			if (!IS_ERR(chan))
2b6d83e2b8b7de Jassi Brar      2014-06-12  471  				break;
2b6d83e2b8b7de Jassi Brar      2014-06-12  472  		}
2b6d83e2b8b7de Jassi Brar      2014-06-12  473  
2b6d83e2b8b7de Jassi Brar      2014-06-12  474  	of_node_put(spec.np);
2b6d83e2b8b7de Jassi Brar      2014-06-12  475  
2d805fc1c6b2ec Benson Leung    2015-05-04  476  	if (IS_ERR(chan)) {
2d805fc1c6b2ec Benson Leung    2015-05-04  477  		mutex_unlock(&con_mutex);
2d805fc1c6b2ec Benson Leung    2015-05-04  478  		return chan;
2d805fc1c6b2ec Benson Leung    2015-05-04  479  	}
2d805fc1c6b2ec Benson Leung    2015-05-04  480  
85a953806557db Elliot Berman   2023-04-10  481  	ret = __mbox_bind_client(chan, cl);
85a953806557db Elliot Berman   2023-04-10  482  	if (ret)
2b6d83e2b8b7de Jassi Brar      2014-06-12  483  		chan = ERR_PTR(ret);

change is set to error pointer

2b6d83e2b8b7de Jassi Brar      2014-06-12  484  
9c57f48cd805b1 Jason-JH.Lin    2024-06-14 @485  	if (chan->mbox->ops->power_put)
                                                            ^^^^^^
Dereferenced on the next line

9c57f48cd805b1 Jason-JH.Lin    2024-06-14  486  		chan->mbox->ops->power_put(chan);
9c57f48cd805b1 Jason-JH.Lin    2024-06-14  487  
2b6d83e2b8b7de Jassi Brar      2014-06-12  488  	mutex_unlock(&con_mutex);
9c57f48cd805b1 Jason-JH.Lin    2024-06-14  489  
2b6d83e2b8b7de Jassi Brar      2014-06-12  490  	return chan;
2b6d83e2b8b7de Jassi Brar      2014-06-12  491  }

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