On 07/08/2013 06:26 PM, Mark Brown wrote: > On Mon, Jul 08, 2013 at 05:48:14PM +0200, Michal Simek wrote: >> On 07/08/2013 04:49 PM, Mark Brown wrote: > >>> Is it definitely safe to leave the IRQ hanging around after the master >>> has been freed - there's no possibility of a late error interrupt or >>> something? > >> I think it is more generic question if this race condition is fine >> for all drivers which are using devres groups. > > Well, it's mainly an issue for IRQs - the other resources don't initiate > events by themselves which is what causes the issue. It just needs a > bit of extra care so I wanted to check that this has been thought of. > >> I have just looked at it and devres_release_all() is called where >> driver is unload and irq are disabled there. > > The problem is the gap between the resources used to handle the IRQ > being freed and the IRQ itself being freed - if the hardware can be > guaranteed to be idle then that's fine but we need to be sure that is > OK. Otherwise the interrupt handler may get run and be looking at a > resource which was freed which would be unfortunate. > >> btw: What's the proper way for spi driver unregistration? > >> spi_unregistered_master() (which also free private structure) >> and >> spi_master_put()? > > Yes.
Just a follow up on this. Which function free private structures registered by spi_alloc_master function? Is it in spi_master_put()? The reason why I am asking is where clk_xx functions should be added. I see them between these two functions in sifr for example. And also I see in drivers in error probe path that drivers are calling kfree(master) but they are not doing in remove part (like spi-davinci.c). I just want to clear this in our zynq drivers before we send them out. Thanks, Michal -- Michal Simek, Ing. (M.Eng), OpenPGP -> KeyID: FE3D1F91 w: www.monstr.eu p: +42-0-721842854 Maintainer of Linux kernel - Microblaze cpu - http://www.monstr.eu/fdt/ Maintainer of Linux kernel - Xilinx Zynq ARM architecture Microblaze U-BOOT custodian and responsible for u-boot arm zynq platform
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