Commit Graph

13 Commits

Author SHA1 Message Date
Linus Torvalds
aa95387774 cpu hotplug: simplify and hopefully fix locking
The CPU hotplug locking was quite messy, with a recursive lock to
handle the fact that both the actual up/down sequence wanted to
protect itself from being re-entered, but the callbacks that it
called also tended to want to protect themselves from CPU events.

This splits the lock into two (one to serialize the whole hotplug
sequence, the other to protect against the CPU present bitmaps
changing). The latter still allows recursive usage because some
subsystems (ondemand policy for cpufreq at least) had already gotten
too used to the lax locking, but the locking mistakes are hopefully
now less fundamental, and we now warn about recursive lock usage
when we see it, in the hope that it can be fixed.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-23 12:12:16 -07:00
Andrew Morton
e2c2770096 [PATCH] hotcpu_notifier-fixes
Always use do {} while (0).  Failing to do so can cause subtle compile
failures or bugs.

Cc: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-01 09:56:03 -07:00
Chandra Seetharaman
39f4885c56 [PATCH] cpu hotplug: add hotplug versions of cpu_notifier
Define new macros register_hotcpu_notifier() and unregister_hotcpu_notifier()
that redefines register_cpu_notifier() and unregister_cpu_notifier() for use
only when HOTPLUG_CPU is defined.

Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-27 17:32:41 -07:00
Chandra Seetharaman
65edc68c34 [PATCH] cpu hotplug: make [un]register_cpu_notifier init time only
CPUs come online only at init time (unless CONFIG_HOTPLUG_CPU is defined).
So, cpu_notifier functionality need to be available only at init time.

This patch makes register_cpu_notifier() available only at init time, unless
CONFIG_HOTPLUG_CPU is defined.

This patch exports register_cpu_notifier() and unregister_cpu_notifier() only
if CONFIG_HOTPLUG_CPU is defined.

Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-27 17:32:41 -07:00
KAMEZAWA Hiroyuki
76b67ed9dc [PATCH] node hotplug: register cpu: remove node struct
With Goto-san's patch, we can add new pgdat/node at runtime.  I'm now
considering node-hot-add with cpu + memory on ACPI.

I found acpi container, which describes node, could evaluate cpu before
memory. This means cpu-hot-add occurs before memory hot add.

In most part, cpu-hot-add doesn't depend on node hot add.  But register_cpu(),
which creates symbolic link from node to cpu, requires that node should be
onlined before register_cpu().  When a node is onlined, its pgdat should be
there.

This patch-set holds off creating symbolic link from node to cpu
until node is onlined.

This removes node arguments from register_cpu().

Now, register_cpu() requires 'struct node' as its argument.  But the array of
struct node is now unified in driver/base/node.c now (By Goto's node hotplug
patch).  We can get struct node in generic way.  So, this argument is not
necessary now.

This patch also guarantees add cpu under node only when node is onlined.  It
is necessary for node-hot-add vs.  cpu-hot-add patch following this.

Moreover, register_cpu calculates cpu->node_id by cpu_to_node() without regard
to its 'struct node *root' argument.  This patch removes it.

Also modify callers of register_cpu()/unregister_cpu, whose args are changed
by register-cpu-remove-node-struct patch.

[Brice.Goglin@ens-lyon.org: fix it]
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Brice Goglin <Brice.Goglin@ens-lyon.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-27 17:32:37 -07:00
Ashok Raj
34f361ade2 [PATCH] Check if cpu can be onlined before calling smp_prepare_cpu()
- Moved check for online cpu out of smp_prepare_cpu()

- Moved default declaration of smp_prepare_cpu() to kernel/cpu.c

- Removed lock_cpu_hotplug() from smp_prepare_cpu() to around it, since
  its called from cpu_up() as well now.

- Removed clearing from cpu_present_map during cpu_offline as it breaks
  using cpu_up() directly during a subsequent online operation.

Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: "Li, Shaohua" <shaohua.li@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-25 08:23:01 -08:00
Andrew Morton
a29d642a4a [PATCH] get_cpu_sysdev() signedness fix
Doing (int < NR_CPUS) doesn't dtrt if it's negative..

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2006-03-20 13:42:59 -08:00
Ashok Raj
a9d9baa1e8 [PATCH] clean up lock_cpu_hotplug() in cpufreq
There are some callers in cpufreq hotplug notify path that the lowest
function calls lock_cpu_hotplug().  The lock is already held during
cpu_up() and cpu_down() calls when the notify calls are broadcast to
registered clients.

Ideally if possible, we could disable_preempt() at the highest caller and
make sure we dont sleep in the path down in cpufreq->driver_target() calls
but the calls are so intertwined and cumbersome to cleanup.

Hence we consistently use lock_cpu_hotplug() and unlock_cpu_hotplug() in
all places.

 - Removed export of cpucontrol semaphore and made it static.
 - removed explicit uses of up/down with lock_cpu_hotplug()
   so we can keep track of the the callers in same thread context and
   just keep refcounts without calling a down() that causes a deadlock.
 - Removed current_in_hotplug() uses
 - Removed PF_HOTPLUG_CPU in sched.h introduced for the current_in_hotplug()
   temporary workaround.

Tested with insmod of cpufreq_stat.ko, and logical online/offline
to make sure we dont have any hang situations.

Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Cc: Zwane Mwaikambo <zwane@linuxpower.ca>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-28 14:42:23 -08:00
Ashok Raj
90d45d17f3 [PATCH] cpu hotplug: fix locking in cpufreq drivers
When calling target drivers to set frequency, we take cpucontrol lock.
When we modified the code to accomodate CPU hotplug, there was an attempt
to take a double lock of cpucontrol leading to a deadlock.  Since the
current thread context is already holding the cpucontrol lock, we dont need
to make another attempt to acquire it.

Now we leave a trace in current->flags indicating current thread already is
under cpucontrol lock held, so we dont attempt to do this another time.

Thanks to Andrew Morton for the beating:-)

From: Brice Goglin <Brice.Goglin@ens-lyon.org>

  Build fix

(akpm: this patch is still unpleasant.  Ashok continues to look for a cleaner
solution, doesn't he?  ;))

Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Brice Goglin <Brice.Goglin@ens-lyon.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-09 07:55:50 -08:00
Ashok Raj
ad74557a49 [PATCH] introduce get_cpu_sysdev() to retrieve a sysfs entry for a cpu.
Some modules creating sysfs entries under /sys/devices/system/cpu/cpuX/
need to know the parent sysfs entry to make devices under them.  This will
just return the sysfs entry for a given cpu.

sysfs entries showing under each cpu sysfs can be easily created if such
entries can be created by registering a sysfs driver for cpuclass.  The
issue is when the entry is created the CPU may not be online, hence we
would need to defer the creation until the online notification comes.

Current users: cache entries for Intel CPU's and cpufreq subsystem.

Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Zwane Mwaikambo <zwane@holomorphy.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-30 17:37:14 -08:00
Rolf Eike Beer
d51fe1be3f [PATCH] remove driverfs references from include/linux/cpu.h and net/sunrpc/rpc_pipe.c
This patch is against 2.6.10, but still applies cleanly. It's just
s/driverfs/sysfs/ in these two files.

Signed-off-by: Rolf Eike Beer <eike-kernel@sf-tec.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-02 00:57:31 -07:00
Ashok Raj
52a119feaa [PATCH] make smp_prepare_cpu to a weak function
I really wish smp_prepare_cpu() would disappear eventually.  In the interim
this is ideally a weak function, so we dont end up changing several places
to define this dummy in headers.

Today since the dummy declaration is done only in drivers/base/cpu.c but
the function is called in kernel/power/smp.c i get undefined reference in
my cpu hotplug code for x86_64 under development.

Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-25 16:24:30 -07:00
Linus Torvalds
1da177e4c3 Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
2005-04-16 15:20:36 -07:00