On 11/18/2012 02:55 PM, Andrew Lunn wrote:
This is not sufficient. In fact it makes no difference at all. The
problem is not with the structure, but with the allocation of memory
used to contain the structure.
pstapriv->pallocated_stainfo_buf = _malloc(sizeof(struct sta_info) *
NUM_STA + 4);
if (pstapriv->pallocated_stainfo_buf == NULL)
return _FAIL;
pstapriv->pstainfo_buf = pstapriv->pallocated_stainfo_buf + 4 -
((addr_t)(pstapriv->pallocated_stainfo_buf) & 3);
kmalloc() guarantees that its alignment is correct for any type of
structure. Thus all this code above is redundant in Linux, but maybe
needed in some other OS. Worse still, this code actually breaks the
alignment. kmalloc() gave out something which was 64 bit aligned. But
by adding 4 and then masking off the lower 2 bits, it destroys the 64
bit alignment and makes it only 32bit aligned.
Removing the _malloc() wrapper, fixing the GFP_ATOMIC, and leaving the
allocater to worry about alignment will be one of the steps to getting
out of staging.
As you surmised, the original driver was meant for several Windows systems as
well as Linux.
This driver will not make it out of staging until it supports the mac80211
stack. Work to accomplish this has started by modifying the rtl8192se code to
work with the USB interface. I will make certain that the alignment issues are
fixed there.
Thanks for the lesson,
Larry
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