Malloc from ISR?

[Joel Sherrill]

See cpukit/libcsupport/src/malloc_deferred.c. It is definitely returning
NULL because
you shouldn't malloc from an ISR. malloc() is a non-deterministic
operation. I am
surprised that code was designed to do that.

Perhaps this code assumes the USB interrupt is serviced from a thread. The
raw
interrupt unblocks a thread to run this code.

--joel

On Mon, Dec 11, 2017 at 6:36 PM, Mr. Andrei Chichak <groups at chichak.ca>
wrote:

> (sorry if this ended up on the Devel list.)
>
> I’m working with ST’s HAL USB stack, and to initialize the various
> structures, they use a USB interrupt as a trigger.
>
> In this interrupt,  they malloc some space for a descriptor (504 bytes).
>
> The RTEMS malloc always returns 0.
>
> Is there a guard against calling malloc in an interrupt context?
>
> I managed to get around the problem by doing a static allocation, but I
> was just wondering.
>
>
> Andrei
>
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