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2006-07-23cpu hotplug: simplify and hopefully fix lockingLinus Torvalds
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>
2006-07-01[PATCH] hotcpu_notifier-fixesAndrew Morton
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>
2006-06-27[PATCH] cpu hotplug: add hotplug versions of cpu_notifierChandra Seetharaman
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[PATCH] cpu hotplug: make [un]register_cpu_notifier init time onlyChandra Seetharaman
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[PATCH] node hotplug: register cpu: remove node structKAMEZAWA Hiroyuki
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>
2006-03-25[PATCH] Check if cpu can be onlined before calling smp_prepare_cpu()Ashok Raj
- 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>
2006-03-20[PATCH] get_cpu_sysdev() signedness fixAndrew Morton
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>
2005-11-28[PATCH] clean up lock_cpu_hotplug() in cpufreqAshok Raj
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>
2005-11-09[PATCH] cpu hotplug: fix locking in cpufreq driversAshok Raj
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>
2005-10-30[PATCH] introduce get_cpu_sysdev() to retrieve a sysfs entry for a cpu.Ashok Raj
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>
2005-09-02[PATCH] remove driverfs references from include/linux/cpu.h and ↵Rolf Eike Beer
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>
2005-06-25[PATCH] make smp_prepare_cpu to a weak functionAshok Raj
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>
2005-04-16Linux-2.6.12-rc2Linus Torvalds
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!