[U-Boot] Bombs away! Was: [PATCH 02/10] net: rtl8139: Add initialized eth_device structure

[Wolfgang Denk]

Dear Reinhard Meyer,

In message <4CB6A3D3.1020506 at emk-elektronik.de> you wrote:
>
> >   		dev = (struct eth_device *)malloc(sizeof *dev);
> > +		memset(dev, 0, sizeof(*dev));
> >
> >   		sprintf (dev->name, "RTL8139#%d", card_number);
> 
> Apparently its quite common NOT to check malloc()'s possible
> NULL return value... At least most NET drivers don't seem to...
> 
> Maybe another RFC to avoid duplicating code:
> 
> malloc_cleared_panic() to allocate and clear memory for a
> really required structure and put a proper panic message if that
> fails. Assuming that continuing u-boot once a driver cannot even
> be initialized is futile, that would save even more code in each
> driver.

Don't invent the wheel. If you really want to take that route, then
copy existing solutions from other projects. Some of them use
xmalloc() for this purpose; see for example BusyBox:
http://git.busybox.net/busybox/tree/libbb/xfuncs_printf.c
lines 44...51

But note that panicing is NOT always the best thing to do. This
shouldbe reserved for really unrecoverable cases only.

Even if you cannot allocate a struct that is essential for your
network driver, then all that is not working is this network driver,
so this is NOT a reason to panic U-Boot. If someone cuts the network
cable or pulls the plug the end effect is the same, and you don;t want
U-Boot to panic because of htat, or do you?

Error handling is important, and needs to be done in a sensible way.

Best regards,

Wolfgang Denk

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