On 26/02/18 21:12, Matthew Wilcox wrote:
[...]

panic() halts the kernel
BUG_ON() kills the thread
WARN_ON() just prints messages

Now, if we're at boot time and we're still executing code from the init
thread, killing init is equivalent to halting the kernel.

The question is, what is appropriate for test modules?  I would say
WARN_ON is not appropriate because people ignore warnings.  BUG_ON is
reasonable for development.  panic() is probably not.

Ok, so I can leave WARN_ON() in the libraries, and keep the more
restrictive BUG_ON() for the self test, which is optional for both
genalloc and pmalloc.

Also, calling BUG_ON while holding a lock is not a good idea; if anything
needs to acquire that lock to shut down in a reasonable fashion, it's
going to hang.

And there's no need to do something like BUG_ON(!foo); foo->wibble = 1;
Dereferencing a NULL pointer already produces a nice informative splat.
In general, we assume other parts of the kernel are sane and if they pass
us a NULL pool, it's no good returning -EINVAL, we may as well just oops
and let somebody else debug it.

Great, that makes the code even simpler.

--
igor

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