Re: [PATCH] usb: gadget: rndis: don't use dev_get_stats()

[David Miller <davem@davemloft.net>]

From: Michal Nazarewicz <m.nazarewicz@samsung.com>
Date: Mon, 20 Sep 2010 20:23:04 +0200

> This commit removes the call to dev_get_stats() from the
> gen_ndis_query_resp() function.  Since spin_lock_bh() was
> added to dev_txq_stats_fold() the call started causing
> warnings.  This is because gen_ndis_query_resp() can be
> (indirectly) called from rndis_command_complete() which is
> called with interrupts disabled.
> 
> While at it, this commit also changes the
> gen_ndis_query_resp() function so that "net" local variable is
> used instead of "rndis_per_dev_params[configNr].dev" in all
> places this is referenced.
> 
> Signed-off-by: Michal Nazarewicz <m.nazarewicz@samsung.com>

The way this works is dev_get_stats() takes that "temp" object the
caller provides, it writes the correct statistics into it (with any
necessary translations), and then passes back a pointer to it.

See net/core/dev.c:dev_get_stats()

You must use dev_get_stats() or else the statistics won't be properly
converted.

Like I originally suggested, you need to rearrange the code in this
driver such that the gen_ndis_query_resp() work happens in a tasklet,
workqueue, or some other non-hardware-irq context.