Date: Tue, 03 Oct 2000 10:59:56 +0200 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: "Jan Mikkelsen" <janm@transactionsite.com> Cc: "John Baldwin" <jhb@FreeBSD.ORG>, "Kevin Mills" <kmills@aventail.com>, "FreeBSD Hackers" <freebsd-hackers@FreeBSD.ORG> Subject: Re: atomic operations Message-ID: <46868.970563596@critter> In-Reply-To: Your message of "Tue, 03 Oct 2000 19:51:16 %2B1100." <005801c02d17$17efc0a0$0901a8c0@haym.transactionsite.com>
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In message <005801c02d17$17efc0a0$0901a8c0@haym.transactionsite.com>, "Jan Mikk elsen" writes: >John Baldwin <jhb@FreeBSD.org> wrote: > >>On 03-Oct-00 Jan Mikkelsen wrote: >>> There shouldn't be a need for a loop like the one you describe for a >simple >>> atomic increment. >> >>The trick is that I want to increment and read at the same time. > > >I don't know the exact semantics of atomic_cmpset_int, but it looks like a >compare and swap operation which returns zero if the operation failed, some >other value on success. That is exactly what atomic_cmpset_int is for, look in sys/fs/devfs/devfs_devs.c for some examples -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD coreteam member | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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