Date: Thu, 5 Jan 2017 02:12:52 -0800 From: "Ngie Cooper (yaneurabeya)" <yaneurabeya@gmail.com> To: Konstantin Belousov <kib@freebsd.org> Cc: src-committers <src-committers@freebsd.org>, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r311287 - head/lib/libc/x86/sys Message-ID: <9DCD3DCE-D1B9-428D-8BD8-E199C37BFC64@gmail.com> In-Reply-To: <201701041610.v04GAq8n068859@repo.freebsd.org> References: <201701041610.v04GAq8n068859@repo.freebsd.org>
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[-- Attachment #1 --] > On Jan 4, 2017, at 08:10, Konstantin Belousov <kib@freebsd.org> wrote: > > Author: kib > Date: Wed Jan 4 16:10:52 2017 > New Revision: 311287 > URL: https://svnweb.freebsd.org/changeset/base/311287 > > Log: > __vdso_gettc(): be extra careful with /dev/hpet mappings, never unmap > the mapping which might be accessed by other threads. > > If a pointer to the /dev/hpet register page mapping was stored into > the hpet_dev_map, other threads might access the page at any time. > Never unmap it, instead, keep track of mappings for all hpet units in > smal array. Store pointer to the newly mapped registers page using > CAS, to detect parallel mappings. > > It appeared relatively easy to demonstrate the problem by arranging > two threads which perform gettimeofday(2) concurently, first time in > the process address space, when HPET is used for timecounter. > > PR: 215715 > Sponsored by: The FreeBSD Foundation > MFC after: 1 week Thank you very much for the work! I’ll try to reproduce the bug again with the ATF test. -Ngie [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Comment: GPGTools - https://gpgtools.org iQIcBAEBCgAGBQJYbhwlAAoJEPWDqSZpMIYVeUMP/A3suUEFM3GkD0rdvgkP8Qhz i8U//978pUHMk2eSEkM0DIllSDnuPawLeQrHRXzesdQUf0v6pGTVDE+4avguZYXW 6ydHVIHZchneA7KkT6uCor03SkN4mxl+GlFbVVQj5YjDUQmazEBJ1GGIqqGLAr0B xZsaKLABLjNSBZLiyFBQBhWmuS7TS4uMPIAURnWYnpnu1rNJ9Xk+56H/3a9NWsHu +RxsYgwK4/h6ClSZUylFoYmzWYr9kThnHK14dX6iGp4iwylGpnhdmLD940Yg67SZ HdLXg+9njYJY5fXk4ihiC7mShmtktzw8lvkZS3AohnE/5bMSuAQtw3X+vcx3DIbq PUxJsfA8NhcXIN7zVBKMyhySCAcz3BrzQcJ78LxDeWXLEiRAM82noOqZSNlZqbKM N1P8kIwjfZCVYVww5/p6gm34hDnrDg3gfDEIPKcA4J5W9xWFCHb6AihWtWfViqCM EY7+lGk1Ln0BQ+/UTQ4VDq0cQWExjGrKrbmteXtkNVNw634O/oolxgElkgioGX/L TI/0ORViI3FvqTjSiOYzxXe70SbV4r+s0GRTPtGLr0vK+9pji8PAMrQZbL3kFcrA 7TYlG2NPzSKLbUPAcqljq26TIHXZDE8TVh3TIq8r5rytL6pNX0BzLrx1KYb7lOsU ZZ3iB1OMHEKqsUSBog0A =ASqr -----END PGP SIGNATURE-----help
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