Hi,
1) man tsleep
2) tsleep is just msleep with NULL mutex.
if you check sys/kern/kern_synch.c you will see KASSERT (ident != NULL && ...
ident is exactly the first parameter.
rik
Norbert Koch:
Hello.
I am just writing a device driver for the i82527 (can-bus) chip. For testing I need the driver to poll the chip instead of running in interrupt mode.
My dev_t read function basically looks like this:
for (;;) { while (chip_has_data(...)) { read_chip_data(...); error = do_uiomove(...); if (error || enough_read(...)) { return error; } }; if (do_not_block_on_read(...)) { return EWOULDBLOCK; } error = tsleep (XXX, PCATCH|PWAIT, "canrd", hz / 10); if (error != EWOULDBLOCK) { return error; } }
XXX should be 'something' which could be used as parameter to wakeup(9), I read in tsleep(9). In the kernel source tree I found one place where tsleep _only_ sleeps: in sys/isa/ppc.c (which already seems to be in the attic [?] but still is in my computer's source tree). Here, the first parameter was set to NULL. Doing this I found, that tsleep immediately returns 0 (which means: wakueup was called) _without_ waiting. I even crashed or froze the kernel by calling tsleep (NULL, ...) for a random number of times. After changing this to the address of the read-function itself, all worked fine. No more crashes.
Just for my understanding: Is this a bug? Does the first parameter have to point to something useful? Is it allowed to point it to a code position? Or should I use some kind of dummy data in the softc structure instead?
What about the second parameter: Is PWAIT ok here or should I use PZERO or whatever?
(And btw, why has ppc.c been removed?)
Thank you.
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