Date: Sat, 12 Jun 2004 22:11:31 -0600 From: Scott Long <scottl@freebsd.org> To: John Polstra <jdp@polstra.com> Cc: freebsd-arch@freebsd.org Subject: Re: RFC: API change for sema_timedwait Message-ID: <40CBD3F3.7040407@freebsd.org> In-Reply-To: <XFMail.20040612121521.jdp@polstra.com> References: <XFMail.20040612121521.jdp@polstra.com>
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John Polstra wrote: > Before 5.x becomes -stable, I'd like to change the API of > sema_timedwait(9). This function is used in only 3 places in the > kernel, all in "dev/ips/ips_commands.c". > > Currently, sema_timedwait returns 0 if the operation fails due to a > timeout. On success, it returns a non-zero value. This is precisely > the opposite of the standard convention in the kernel, where 0 means > success and a non-zero value (taken from <sys/errno.h>) means failure. > The convention exists because most functions can succeed in only one > way but can fail in several different ways. > > The reason I care about this is because I'd like to add new functions > sema_wait_sig() and sema_timedwait_sig() which can be interrupted > by a signal. Then sema_timedwait_sig could fail in two different > ways: as a result of a timeout or as a result of a signal. If these > functions returned proper errno values on failure, it would be easy to > distinguish between the two failure cases. > > This change would also make the return values of sema_timedwait, > sema_wait_sig, and sema_timedwait_sig consistent with the analogous > condition variable operations cv_timedwait, cv_wait_sig, and > cv_timedwait_sig and with tsleep and msleep. > > Does this change sound OK to you folks? > > John Being the ips maintainer, I have no objection to this change. Scott
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