Re: [PATCH] Document kfree and vfree NULL usage

From: linux
Date: Sat Nov 27 2004 - 17:18:47 EST


>> - if (mfile) {
>> - kfree(mfile);
>> - } else {
>> + kfree(mfile);
>> + if (!mfile) {
>> snd_printk(KERN_ERR "ALSA card file remove problem (%p)\n", file);
>> return -ENOENT;
>> }

> The above change seems to always trigger the ENOENT return, no?

No. kfree(mfile) doesn't magically change the numerical value of mfile.
Dereferencing it now would be a bad idea, but you can still look at it.

(The ANSI C standard envisions architectures on which just *looking* at
a dangling pointer is illegal, but Linux makes slightly tighter
restrictions.)
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