Ran it with gdb, reproduced, and then interrupted when it started consuming 100% CPU:

Thread 1 "pcscd" received signal SIGINT, Interrupt.
0x00007ffff74e2853 in select () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) bt
#0  0x00007ffff74e2853 in select () from /lib/x86_64-linux-gnu/libc.so.6
#1  0x0000000000411cfd in ProcessEventsServer (pdwClientID=pdwClientID@entry=0x7fffffffe49c) at winscard_msg_srv.c:223
#2  0x00000000004037f9 in SVCServiceRunLoop () at pcscdaemon.c:128
#3  main (argc=<optimized out>, argv=<optimized out>) at pcscdaemon.c:685
(gdb) info threads
  Id   Target Id         Frame 
* 1    Thread 0x7ffff7fb9740 (LWP 18298) "pcscd" 0x00007ffff74e2853 in select () from /lib/x86_64-linux-gnu/libc.so.6
  2    Thread 0x7ffff6fb0700 (LWP 18302) "pcscd" 0x00007ffff74e09ed in poll () from /lib/x86_64-linux-gnu/libc.so.6
  3    Thread 0x7ffff67af700 (LWP 18303) "pcscd" 0x00007ffff74e09ed in poll () from /lib/x86_64-linux-gnu/libc.so.6
  4    Thread 0x7ffff5fae700 (LWP 18304) "pcscd" 0x00007ffff74e09ed in poll () from /lib/x86_64-linux-gnu/libc.so.6
  5    Thread 0x7ffff57ad700 (LWP 18305) "pcscd" 0x00007ffff74e09ed in poll () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) thread 2
[Switching to thread 2 (Thread 0x7ffff6fb0700 (LWP 18302))]
#0  0x00007ffff74e09ed in poll () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) bt
#0  0x00007ffff74e09ed in poll () from /lib/x86_64-linux-gnu/libc.so.6
#1  0x00007ffff6fc064c in ?? () from /lib/x86_64-linux-gnu/libusb-1.0.so.0
#2  0x00007ffff77b666a in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0
#3  0x00007ffff74ec01d in clone () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) thread 3
[Switching to thread 3 (Thread 0x7ffff67af700 (LWP 18303))]
#0  0x00007ffff74e09ed in poll () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) bt
#0  0x00007ffff74e09ed in poll () from /lib/x86_64-linux-gnu/libc.so.6
#1  0x00007ffff6fc064c in ?? () from /lib/x86_64-linux-gnu/libusb-1.0.so.0
#2  0x00007ffff77b666a in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0
#3  0x00007ffff74ec01d in clone () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) thread 4
[Switching to thread 4 (Thread 0x7ffff5fae700 (LWP 18304))]
#0  0x00007ffff74e09ed in poll () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) bt
#0  0x00007ffff74e09ed in poll () from /lib/x86_64-linux-gnu/libc.so.6
#1  0x00007ffff6fb9bc5 in ?? () from /lib/x86_64-linux-gnu/libusb-1.0.so.0
#2  0x00007ffff6fbab53 in libusb_handle_events_timeout_completed () from /lib/x86_64-linux-gnu/libusb-1.0.so.0
#3  0x00007ffff6fbac3f in libusb_handle_events () from /lib/x86_64-linux-gnu/libusb-1.0.so.0
#4  0x00007ffff71d64bc in ?? () from /usr/lib/pcsc/drivers/ifd-ccid.bundle/Contents/Linux/libccid.so
#5  0x00007ffff71d0b83 in ?? () from /usr/lib/pcsc/drivers/ifd-ccid.bundle/Contents/Linux/libccid.so
#6  0x00000000004064db in EHStatusHandlerThread (rContext=0x61f010) at eventhandler.c:464
#7  0x00007ffff77b666a in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0
#8  0x00007ffff74ec01d in clone () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) thread 5
[Switching to thread 5 (Thread 0x7ffff57ad700 (LWP 18305))]
#0  0x00007ffff74e09ed in poll () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) bt
#0  0x00007ffff74e09ed in poll () from /lib/x86_64-linux-gnu/libc.so.6
#1  0x000000000040eeaa in poll (__timeout=-1, __nfds=1, __fds=0x7ffff57aced0) at /usr/include/x86_64-linux-gnu/bits/poll2.h:46
#2  HPEstablishUSBNotifications (arg=0x649910) at hotplug_libudev.c:624
#3  0x00007ffff77b666a in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0
#4  0x00007ffff74ec01d in clone () from /lib/x86_64-linux-gnu/libc.so.6