Date: Fri, 07 Jun 2002 11:18:30 -0700 From: Terry Lambert <tlambert2@mindspring.com> To: John Baldwin <jhb@FreeBSD.org> Cc: arch@FreeBSD.org Subject: Re: KTRACE genio trace question Message-ID: <3D00F8F6.D020EB53@mindspring.com> References: <XFMail.20020607123531.jhb@FreeBSD.org>
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John Baldwin wrote: > green changed this in revision 1.37 of kern_ktrace.c to instead > use a copy of the original uio and split the write operation into > two VOP_WRITE's. However, this can result in a corrupt tracefile if > the first VOP_WRITE succeeds but the second one fails. Under what circumstances is this possible, such that the original code would *not* have also failed on the second loop through the uiomove code? > Also, since we defer the copyin() until the VOP_WRITE, the actual > VOP_WRITE needs to be done by the original thread requiring ugly > synchronization between the ktrace worker thread and the thread > submitting a trace request. I don't understand this requirement; all threads in a thread group have identical references to the same address spaces. Therefore, as long as you have the correct process, you shouldn't care, right? -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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