Date: Fri, 12 Sep 2008 10:22:35 -0400 From: John Baldwin <jhb@freebsd.org> To: Konstantin Belousov <kib@freebsd.org> Cc: cvs-src@freebsd.org, src-committers@freebsd.org, cvs-all@freebsd.org Subject: Re: cvs commit: src/sys/i386/i386 sys_machdep.c Message-ID: <200809121022.36441.jhb@freebsd.org> In-Reply-To: <200809120951.m8C9pOZj037333@repoman.freebsd.org> References: <200809120951.m8C9pOZj037333@repoman.freebsd.org>
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On Friday 12 September 2008 05:51:11 am Konstantin Belousov wrote: > kib 2008-09-12 09:51:11 UTC > > FreeBSD src repository > > Modified files: > sys/i386/i386 sys_machdep.c > Log: > SVN rev 182960 on 2008-09-12 09:51:11Z by kib > > The user_ldt_alloc() function shall return with dt_lock locked. > The user_ldt_free() function shall return with dt_lock unlocked. > Error handling code in both functions do not handle this, fix it by > doing necessary lock/unlock. > > While there, fix minor style nits. Hmm, I had actually thought it was intentional for user_ldt_alloc() to only return with the lock held on success and depend on a later call to another method to drop the lock in the success case (so the locking isn't visible to consumers of the API in theory). For example, i386_ldt_grow() depended on this feature and is now broken (it leaks a lock on failure). I missed this when looking at this yesterday. Other notes: - Since user_ldt_free() handles the case of there not being an LDT, the code in exec_setregs() on i386 can be simplified to just always call user_ldt_free(). - cpu_exit() could possibly do the same. I wonder if exec_setregs() needs the same fixup to %gs that cpu_exit() does. If so, that could possibly be moved into user_ldt_free(). Ah, exec_setregs() does it unconditionally. I think you could make cpu_exit() just do it unconditionally as well before calling user_ldt_free(). -- John Baldwin
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