Package: util-linux
Version: 2.41-5
Severity: normal
Dear Maintainer,
while strace'ing to find out why hardlink is so slow, IO found it does this
sequence between every fstatat call:
gettid() = 36482
getpid() = 36482
tgkill(36482, 36482, 0) = 0
this seems to be a pretty weird thing to do in a tighht scanning
loop. Looking at the code, handle_interrupt is responsible:
/**
* handle_interrupt - Handle a signal
*/
static void handle_interrupt(void)
{
switch (last_signal) {
case SIGUSR1:
print_stats();
putchar('\n');
break;
default:
signal(last_signal, SIG_DFL);
raise(last_signal);
break;
}
last_signal = 0;
}
this is already a weird function to begin with, but crucially, it calls
signal(0,... and raise(0).
it seems to me the former is likely undefined behaviour and the latter is
just unnecessartily slow.
most likely, handle_interrupt simply should not be called after every fstatat,
or at all, without last_signal bering set beforehand.
-- System Information:
Debian Release: 13.5
APT prefers stable-updates
APT policy: (990, 'stable-updates'), (990, 'stable-security'), (990,
'stable'), (500, 'unstable'), (500, 'testing'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386, x32
Kernel: Linux 6.12.90+deb13.1-amd64 (SMP w/28 CPU threads; PREEMPT)
Kernel taint flags: TAINT_USER, TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=en_IE.UTF-8, LC_CTYPE=en_IE.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled
Versions of packages util-linux depends on:
ii libblkid1 2.41-5
ii libc6 2.41-12+deb13u3
ii libcap-ng0 0.8.5-4+b1
ii libcrypt1 1:4.4.38-1
ii liblastlog2-2 2.41-5
ii libmount1 2.41-5
ii libpam-modules 1.7.0-5
ii libpam-runtime 1.7.0-5
ii libpam0g 1.7.0-5
ii libselinux1 3.8.1-1
ii libsmartcols1 2.41-5
ii libsystemd0 257.13-1~deb13u1
ii libtinfo6 6.5+20250216-2
ii libudev1 257.13-1~deb13u1
ii libuuid1 2.41-5
Versions of packages util-linux recommends:
ii sensible-utils 0.0.25
Versions of packages util-linux suggests:
ii dosfstools 4.2-1.2
ii kbd 2.7.1-2
ii util-linux-extra 2.41-5
pn util-linux-locales <none>
ii wtmpdb 0.73.0-3+deb13u1
-- no debconf information
