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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] Fix locking in tools/hotplug/Linux/locking.sh
On Mon, 2012-11-12 at 18:40 +0000, Olaf Hering wrote:
> On Mon, Nov 12, Jacek Konieczny wrote:
>
> > # perl --version
> > This is perl, v5.8.8 built for x86_64-pld-linux-thread-multi
>
> sles11sp2 has perl 5.10.0, maybe there is different behaviour in
> different perl versions.
More likely to be the kernel, since Perl would have to jump through
hoops to figure out if a random fd which it got passed was r/o or r/w, I
think.
Perhaps its a security thing (e.g. selinux or something like that)
enforcing something extra?
Might be interesting to run things under strace ? Per the attached t.sh.
Which for me produces the below without complaint:
Ian.
+ _lockfd=42
+ _lockfile=/tmp/lockfile
+ eval 'exec 42>>/tmp/lockfile'
++ exec
+ flock -x 42
++ strace perl -e '
open STDIN, "<&42" or die $!;
my $fd_inum = (stat STDIN)[1]; die $! unless defined $fd_inum;
my $file_inum = (stat $ARGV[0])[1];
print "y\n" if $fd_inum eq $file_inum;
' /tmp/lockfile
execve("/usr/bin/perl", ["perl", "-e", "\n open STDIN, \"<&42\"
"..., "/tmp/lockfile"], [/* 35 vars */]) = 0
brk(0) = 0xea0000
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0x7f08728d7000
access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=68197, ...}) = 0
mmap(NULL, 68197, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f08728c6000
close(3) = 0
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
open("/usr/lib/libperl.so.5.10", O_RDONLY) = 3
read(3,
"\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\220\222\3\0\0\0\0\0"..., 832) =
832
fstat(3, {st_mode=S_IFREG|0644, st_size=1495208, ...}) = 0
mmap(NULL, 3590856, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) =
0x7f087234f000
mprotect(0x7f08724b4000, 2093056, PROT_NONE) = 0
mmap(0x7f08726b3000, 36864, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x164000) = 0x7f08726b3000
close(3) = 0
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
open("/lib/libdl.so.2", O_RDONLY) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\340\r\0\0\0\0\0\0"...,
832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=14696, ...}) = 0
mmap(NULL, 2109696, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) =
0x7f087214b000
mprotect(0x7f087214d000, 2097152, PROT_NONE) = 0
mmap(0x7f087234d000, 8192, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x2000) = 0x7f087234d000
close(3) = 0
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
open("/lib/libm.so.6", O_RDONLY) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\360>\0\0\0\0\0\0"...,
832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=530736, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0x7f08728c5000
mmap(NULL, 2625768, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) =
0x7f0871ec9000
mprotect(0x7f0871f49000, 2097152, PROT_NONE) = 0
mmap(0x7f0872149000, 8192, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x80000) = 0x7f0872149000
close(3) = 0
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
open("/lib/libpthread.so.0", O_RDONLY) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\360Y\0\0\0\0\0\0"...,
832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=131258, ...}) = 0
mmap(NULL, 2208640, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) =
0x7f0871cad000
mprotect(0x7f0871cc4000, 2093056, PROT_NONE) = 0
mmap(0x7f0871ec3000, 8192, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x16000) = 0x7f0871ec3000
mmap(0x7f0871ec5000, 13184, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f0871ec5000
close(3) = 0
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
open("/lib/libc.so.6", O_RDONLY) = 3
read(3,
"\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\240\355\1\0\0\0\0\0"..., 832) =
832
fstat(3, {st_mode=S_IFREG|0755, st_size=1437064, ...}) = 0
mmap(NULL, 3545160, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) =
0x7f087194b000
mprotect(0x7f0871aa4000, 2093056, PROT_NONE) = 0
mmap(0x7f0871ca3000, 20480, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x158000) = 0x7f0871ca3000
mmap(0x7f0871ca8000, 18504, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f0871ca8000
close(3) = 0
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
open("/lib/libcrypt.so.1", O_RDONLY) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0P\n\0\0\0\0\0\0"...,
832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=35104, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0x7f08728c4000
mmap(NULL, 2318784, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) =
0x7f0871714000
mprotect(0x7f087171c000, 2093056, PROT_NONE) = 0
mmap(0x7f087191b000, 8192, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x7000) = 0x7f087191b000
mmap(0x7f087191d000, 184768, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f087191d000
close(3) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0x7f08728c3000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0x7f08728c2000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
0x7f08728c1000
arch_prctl(ARCH_SET_FS, 0x7f08728c2700) = 0
mprotect(0x7f087191b000, 4096, PROT_READ) = 0
mprotect(0x7f0871ca3000, 16384, PROT_READ) = 0
mprotect(0x7f0871ec3000, 4096, PROT_READ) = 0
mprotect(0x7f0872149000, 4096, PROT_READ) = 0
mprotect(0x7f087234d000, 4096, PROT_READ) = 0
mprotect(0x7f08728d9000, 4096, PROT_READ) = 0
munmap(0x7f08728c6000, 68197) = 0
set_tid_address(0x7f08728c29d0) = 17761
set_robust_list(0x7f08728c29e0, 0x18) = 0
futex(0x7fffbb03b91c, FUTEX_WAKE_PRIVATE, 1) = 0
futex(0x7fffbb03b91c, FUTEX_WAIT_BITSET_PRIVATE|FUTEX_CLOCK_REALTIME, 1, NULL,
7f08728c2700) = -1 EAGAIN (Resource temporarily unavailable)
rt_sigaction(SIGRTMIN, {0x7f0871cb2870, [], SA_RESTORER|SA_SIGINFO,
0x7f0871cbbff0}, NULL, 8) = 0
rt_sigaction(SIGRT_1, {0x7f0871cb2900, [], SA_RESTORER|SA_RESTART|SA_SIGINFO,
0x7f0871cbbff0}, NULL, 8) = 0
rt_sigprocmask(SIG_UNBLOCK, [RTMIN RT_1], NULL, 8) = 0
getrlimit(RLIMIT_STACK, {rlim_cur=8192*1024, rlim_max=RLIM_INFINITY}) = 0
rt_sigaction(SIGFPE, {SIG_IGN, [FPE], SA_RESTORER|SA_RESTART, 0x7f087197d230},
{SIG_DFL, [], 0}, 8) = 0
brk(0) = 0xea0000
brk(0xec1000) = 0xec1000
getuid() = 1161
geteuid() = 1161
getgid() = 10020
getegid() = 10020
open("/usr/lib/locale/locale-archive", O_RDONLY) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=2018512, ...}) = 0
mmap(NULL, 2018512, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f0871527000
close(3) = 0
open("/dev/urandom", O_RDONLY) = 3
read(3, "\346\340\354H", 4) = 4
close(3) = 0
readlink("/proc/self/exe", "/usr/bin/perl", 4095) = 13
stat("/usr/local/lib/site_perl/5.10.1/x86_64-linux-gnu-thread-multi",
0x7fffbb03b390) = -1 ENOENT (No such file or directory)
stat("/usr/local/lib/site_perl/5.10.1", 0x7fffbb03b390) = -1 ENOENT (No such
file or directory)
stat("/usr/local/lib/site_perl/x86_64-linux-gnu-thread-multi", 0x7fffbb03b390)
= -1 ENOENT (No such file or directory)
stat("/usr/local/lib/perl/5.10.0", 0x7fffbb03b4d0) = -1 ENOENT (No such file or
directory)
stat("/usr/local/share/perl/5.10.0", 0x7fffbb03b4d0) = -1 ENOENT (No such file
or directory)
ioctl(0, SNDCTL_TMR_TIMEBASE or TCGETS, {B38400 opost isig icanon echo ...}) = 0
lseek(0, 0, SEEK_CUR) = -1 ESPIPE (Illegal seek)
ioctl(1, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fffbb03b260) = -1 EINVAL (Invalid
argument)
lseek(1, 0, SEEK_CUR) = -1 ESPIPE (Illegal seek)
ioctl(2, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fffbb03b270) = -1 ENOTTY
(Inappropriate ioctl for device)
lseek(2, 0, SEEK_CUR) = 7954
open("/dev/null", O_RDONLY) = 3
ioctl(3, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fffbb03b390) = -1 ENOTTY
(Inappropriate ioctl for device)
lseek(3, 0, SEEK_CUR) = 0
fcntl(3, F_SETFD, FD_CLOEXEC) = 0
fstat(3, {st_mode=S_IFCHR|0666, st_rdev=makedev(1, 3), ...}) = 0
rt_sigaction(SIGCHLD, NULL, {SIG_DFL, [], 0}, 8) = 0
brk(0xee2000) = 0xee2000
close(3) = 0
dup(42) = 3
ioctl(3, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fffbb03b320) = -1 ENOTTY
(Inappropriate ioctl for device)
lseek(3, 0, SEEK_CUR) = 0
fstat(3, {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
dup2(3, 0) = 0
close(3) = 0
fcntl(0, F_SETFD, 0) = 0
fstat(0, {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
stat("/tmp/lockfile", {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
rt_sigaction(SIG_0, NULL, {0x7fffbb03b810, ~[HUP INT QUIT TRAP BUS FPE USR1
SEGV USR2 TERM CONT TTIN TTOU URG XFSZ PROF WINCH RTMIN RT_1 RT_2 RT_3 RT_5
RT_6 RT_7 RT_8 RT_16 RT_17 RT_18 RT_19 RT_20 RT_21 RT_22 RT_23 RT_24 RT_25
RT_26 RT_27 RT_28 RT_29 RT_30 RT_31], 0}, 8) = -1 EINVAL (Invalid argument)
rt_sigaction(SIGHUP, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGINT, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGQUIT, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGILL, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGTRAP, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGABRT, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGBUS, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGFPE, NULL, {SIG_IGN, [FPE], SA_RESTORER|SA_RESTART,
0x7f087197d230}, 8) = 0
rt_sigaction(SIGKILL, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGUSR1, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGSEGV, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGUSR2, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGPIPE, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGALRM, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGTERM, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGSTKFLT, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGCHLD, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGCONT, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGSTOP, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGTSTP, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGTTIN, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGTTOU, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGURG, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGXCPU, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGXFSZ, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGVTALRM, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGPROF, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGWINCH, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGIO, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGPWR, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGSYS, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_2, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_3, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_4, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_5, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_6, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_7, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_8, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_9, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_10, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_11, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_12, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_13, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_14, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_15, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_16, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_17, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_18, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_19, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_20, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_21, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_22, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_23, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_24, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_25, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_26, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_27, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_28, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_29, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_30, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_31, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGRT_32, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGABRT, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGCHLD, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGIO, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigaction(SIGSYS, NULL, {SIG_DFL, [], 0}, 8) = 0
write(1, "y\n", 2) = 2
exit_group(0) = ?
+ rightfile=y
+ echo y
Attachment:
t.sh _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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