Messages in this thread | | | Date | Wed, 29 Jun 2005 09:44:52 -0400 (EDT) | From | Steven Rostedt <> | Subject | Re: kmalloc without GFP_xxx? |
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On Wed, 29 Jun 2005, Arjan van de Ven wrote: > > > > but it sets irqs_disabled() IIRC. > > only spin_lock_irq() and co do. > not the simple spin_lock() >
It may be dangerous to use spin_lock with interrupts enabled, since you have to make sure that no interrupt ever grabs that lock. Although I do recall seeing a few locks like this. But even so, you can transfer the latency of the interrupts going off while holding that lock to another CPU which IMHO is a bad thing. Also a simple spin_lock would disable preemption with CONFIG_PREEMPT set and that would make in_atomic fail. But to implement a kmalloc_auto you would always need to have a preempt count.
I'm not for a kmalloc_auto, but something like it would be useful for a function that can work for either context, and just fail nicely if the ATOMIC is set and the malloc can't get memory. A function like this would currently have to always use ATOMIC even if it could have used KERNEL for some scenarios, since it would suffer the same pitfalls as a kmalloc_auto in determining its context.
-- Steve
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