Date: Thu, 5 Sep 2019 23:12:07 +0000 (UTC) From: Warner Losh <imp@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-12@freebsd.org Subject: svn commit: r351909 - stable/12/sys/dev/nvme Message-ID: <201909052312.x85NC7Ea032573@repo.freebsd.org>
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Author: imp Date: Thu Sep 5 23:12:06 2019 New Revision: 351909 URL: https://svnweb.freebsd.org/changeset/base/351909 Log: MFC r351704: Add a brief comment explaining why we can return ETIMEDOUT from the call to the polled interface. Normally this would have the potential to corrupt stack memory because the completion routines would run after we return. In this case, however, we're doing a dump so it's safe for reasons explained in the comment. Modified: stable/12/sys/dev/nvme/nvme_ns_cmd.c Directory Properties: stable/12/ (props changed) Modified: stable/12/sys/dev/nvme/nvme_ns_cmd.c ============================================================================== --- stable/12/sys/dev/nvme/nvme_ns_cmd.c Thu Sep 5 23:09:50 2019 (r351908) +++ stable/12/sys/dev/nvme/nvme_ns_cmd.c Thu Sep 5 23:12:06 2019 (r351909) @@ -191,6 +191,14 @@ nvme_ns_dump(struct nvme_namespace *ns, void *virt, of nvme_qpair_process_completions(req->qpair); } + /* + * Normally, when using the polling interface, we can't return a + * timeout error because we don't know when the completion routines + * will be called if the command later completes. However, in this + * case we're running a system dump, so all interrupts are turned + * off, the scheduler isn't running so there's nothing to complete + * the transaction. + */ if (status.done == FALSE) return (ETIMEDOUT);
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