On 2/23/22 5:30 PM, 'Andy Shevchenko' wrote: > On Wed, Feb 23, 2022 at 09:44:32PM +0000, David Laight wrote: >> From: Andy Shevchenko >>> Sent: 23 February 2022 18:54 >>> >>> While in this particular case it would not be a (critical) issue, >>> the pattern itself is bad and error prone in case somebody blindly >>> copies to their code. >> >> It is horribly wrong on BE systems. > > You mean the pattern? Yes, it has three issues regarding to endianess and > potential out of boundary access. > > ... > >>> - return handled; >>> + return IRQ_RETVAL(!bitmap_empty(pending, CCE_NUM_INT_CSRS * 64)); > >> You really don't want to scan the bitmap again. > > Either way it wastes cycles, the outcome depends on the actual distribution of > the interrupts across the bitmap. If it gathered closer to the beginning of the > bitmap, my code wins, otherwise the original ones. > >> Actually, of the face of it, you could merge the two loops. >> Provided you clear the status bit before calling the relevant >> handler I expect it will all work. > > True. I will consider that for v2. Will wait for a v2 patch and I'll test it. We are very sensitive to performance changes. -Denny
