Change in flashrom[master]: linux_spi.c: Refactor singleton states into reentrant pattern

[Nico Huber (Code Review)]

Attention is currently required from: Anastasia Klimchuk.
Nico Huber has posted comments on this change. ( https://review.coreboot.org/c/flashrom/+/52285 )

Change subject: linux_spi.c: Refactor singleton states into reentrant pattern
......................................................................

Patch Set 3:

(6 comments)

File linux_spi.c:

https://review.coreboot.org/c/flashrom/+/52285/comment/c7e44348_638a1c05 
PS3, Line 111: const
Why drop it?

Ah, I've seen how it's used below now. Seems to counteract
the idea of reentrant, though, doesn't it?

I know you have plans to change the API, so it doesn't really
matter now.

https://review.coreboot.org/c/flashrom/+/52285/comment/626751e4_b00e0fa0 
PS3, Line 71: (struct linux_spi_data *) 
Nit, generally no need to cast `void *` to anything.

https://review.coreboot.org/c/flashrom/+/52285/comment/b86dc368_a298271f 
PS3, Line 72: 	if (spi_data->fd != -1)
Seems impossible to fail?

https://review.coreboot.org/c/flashrom/+/52285/comment/96a9c39b_2df9ba92 
PS3, Line 177:  -1
Where would this be consumed?

https://review.coreboot.org/c/flashrom/+/52285/comment/b1ab9d52_e66e36f0 
PS3, Line 242: 		ret = SPI_GENERIC_ERROR;
FWIW, this and the related definitions are part of the SPI command
API and not for initialization.

https://review.coreboot.org/c/flashrom/+/52285/comment/575aacfc_035fc7a5 
PS3, Line 260: 		fd = -1;
It's a local variable now, making this dead code.