Date: Tue, 30 Jan 2001 08:25:53 +0600 (ALMT) From: Boris Popov <bp@freebsd.org> To: Bosko Milekic <bmilekic@technokratis.com> Cc: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/kern kern_malloc.c src/sys/sys malloc.h Message-ID: <Pine.BSF.4.21.0101300813090.46219-100000@lion.butya.kz> In-Reply-To: <00ff01c08a2a$f4d98710$1f90c918@jehovah>
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On Mon, 29 Jan 2001, Bosko Milekic wrote: > > Add M_PANIC flag to the list of available flags passed to > malloc(). > > With this flag set malloc() will panic if memory allocation > failed. > > This usable only in critical places where failed allocation is > fatal. > > Why is this change necessary? Rather, how is this change correct? I'd > rather not introduce this sort of thing into the actual interface, > unless it's realistically necessary, as I can see how this may > encourage some people writing drivers (or an equivalent) to decide > that they ought to panic the machine if they can't allocate. I'd > rather see this dealt with, where absolutely necessary, by calling > malloc() with M_NOWAIT and checking the return value and then calling > panic explicitly if it is NULL. As commit message states, this flag should be used only as a last resort and only in really critical places where it is impossible to continue if memory allocation failed. In my case it saved a lots of 'if (blah == NULL) panic()' in the specific subsystem (in the terms of saved bytes in the code segment, not extra lines in the source file). This is completely safe in this case because kernel will be completely broken if one of malloc()s failed. -- Boris Popov http://www.butya.kz/~bp/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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