Subject: Re: [PATCH net-next] net: phy: fixed_phy: replace list of fixed PHYs with static array

From: Jakub Kicinski <[email-masked]>
Date: Fri, 9 Jan 2026 08:31:30 -0800

On Fri, 9 Jan 2026 15:10:18 +0000 Russell King (Oracle) wrote:
> > Isn't IDA an overkill for a range this tiny?
> > IDA is useful if the ID range is large and may be sparse.
> > Here a bitmap would suffice.
> > 
> > DECLARE_BITMAP(phy_fixed_ids, NUM_FP); 
> > 
> > id = find_first_zero_bit(phy_fixed_ids, NUM_FP);
> > if (id >= NUM_FP)
> > 	return -ENOSPC;
> > 
> > set_bit(id, phy_fixed_ids);  
> 
> Racy without locking.

True, if there's no existing locking wrap it in a do {} while and use
test_and_set_bit() as the condition for repeat.