linux-kernel - question about drivers/power/88pm860x

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Message-ID: <alpine.DEB.2.02.1212081731080.1984@hadrien>
Date:	Sat, 8 Dec 2012 17:37:45 +0100 (CET)
From:	Julia Lawall <julia.lawall@...6.fr>
To:	cbou@...l.ru, dwmw2@...radead.org, linux-kernel@...r.kernel.org
Subject: question about drivers/power/88pm860x_charger.c

The function pm860x_charger_probe in the file 
drivers/power/88pm860x_charger.c contains the following code:

         count = pdev->num_resources;
         for (i = 0, j = 0; i < count; i++) {
                 info->irq[j] = platform_get_irq(pdev, i);
                 if (info->irq[j] < 0)
                         continue;
                 j++;
         }
         info->irq_nums = j;

and then later the following code:

        for (i = 0; i < ARRAY_SIZE(info->irq); i++) {
                 ret = request_threaded_irq(info->irq[i], NULL,
                         pm860x_irq_descs[i].handler,
                         IRQF_ONESHOT, pm860x_irq_descs[i].name, info);
 		...
         }

and finally, in the function pm860x_charger_remove, the code:

         free_irq(info->irq[0], info);
         for (i = 0; i < info->irq_nums; i++)
                 free_irq(info->irq[i], info);

It looks like the irq_nums field is being used to record how many 
platform_get_irq calls were successful, but this information is not used 
in the second block of code, where request_threaded_irq is called.  So it 
would seem that all of the requested irqs should be freed, and not just 
the first irq_nums of them.

The remove code also looks like a double free of info->irq[0].

Could I just get rid of the irq_nums field completely?  It doesn't seem to 
be used elsewhere.  Also, I was planning to use devm_request_threaded_irq, 
so then there won't be a need for the explicit frees at all.

This file also contains a kfree of devm_kzalloc'd data, which is why I 
looked at it in the first place.

thanks,
julia
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