perf/x86/intel/rapl: Make package handling more robust

The package management code in RAPL relies on package mapping being
available before a CPU is started. This changed with:

  9d85eb9119f4 ("x86/smpboot: Make logical package management more robust")

because the ACPI/BIOS information turned out to be unreliable, but that
left RAPL in broken state. This was not noticed because on a regular boot
all CPUs are online before RAPL is initialized.

A possible fix would be to reintroduce the mess which allocates a package
data structure in CPU prepare and when it turns out to already exist in
starting throw it away later in the CPU online callback. But that's a
horrible hack and not required at all because RAPL becomes functional for
perf only in the CPU online callback. That's correct because user space is
not yet informed about the CPU being onlined, so nothing caan rely on RAPL
being available on that particular CPU.

Move the allocation to the CPU online callback and simplify the hotplug
handling. At this point the package mapping is established and correct.

This also adds a missing check for available package data in the
event_init() function.

Reported-by: Yasuaki Ishimatsu <yasu.isimatu@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Fixes: 9d85eb9119f4 ("x86/smpboot: Make logical package management more robust")
Link: http://lkml.kernel.org/r/20170131230141.212593966@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

path: root/net/dns_resolver/Kconfig

#
# Configuration for DNS Resolver
#
config DNS_RESOLVER
	tristate "DNS Resolver support"
	depends on NET && KEYS
	help
	  Saying Y here will include support for the DNS Resolver key type
	  which can be used to make upcalls to perform DNS lookups in
	  userspace.

	  DNS Resolver is used to query DNS server for information.  Examples
	  being resolving a UNC hostname element to an IP address for CIFS or
	  performing a DNS query for AFSDB records so that AFS can locate a
	  cell's volume location database servers.

	  DNS Resolver is used by the CIFS and AFS modules, and would support
	  SMB2 later.  DNS Resolver is supported by the userspace upcall
	  helper "/sbin/dns.resolver" via /etc/request-key.conf.

	  See <file:Documentation/networking/dns_resolver.txt> for further
	  information.

	  To compile this as a module, choose M here: the module will be called
	  dnsresolver.

	  If unsure, say N.