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This patch updates the comments to match the actual code.
Signed-off-by: Martin Waitz <tali@admingilde.org>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
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I was grepping through the code and some `grep ganularity -R .` didn't
catch what I thought. Then looking closer I saw the term "granuality"
used in only four places (in comments) and granularity in many more
places describing the same idea. Some other facts:
dictionary.com does not know such a word
define:granuality on google is not found (and pages for granuality are
mostly related to patches to the kernel)
it has not been discussed as a term on LKML, AFAICS (=Can Search)
To be consistent, I think granularity should be used everywhere.
Signed-off-by: Kalin KOZHUHAROV <kalin@thinrope.net>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
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* master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6:
[NET]: Allow skb headroom to be overridden
[TCP]: Kill unused extern decl for tcp_v4_hash_connecting()
[NET]: add SO_RCVBUF comment
[NET]: Deinline some larger functions from netdevice.h
[DCCP]: Use NULL for pointers, comfort sparse.
[DECNET]: Fix refcount
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As announced, lookup_hash() can now become static.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The monochrome->color expansion routine that handles bitmaps which have
(widths % 8) != 0 (slow_imageblit) produces corrupt characters in big-endian.
This is caused by a bogus bit test in slow_imageblit().
Fix.
This patch may deserve to go to the stable tree. The code has already been
well tested in little-endian machines. It's only in big-endian where there is
uncertainty and Herbert confirmed that this is the correct way to go.
It should not introduce regressions.
Signed-off-by: Antonino Daplas <adaplas@pol.net>
Acked-by: Herbert Poetzl <herbert@13thfloor.at>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Backlight class attributes are currently easy to implement incorrectly.
Moving certain handling into the backlight core prevents this whilst at the
same time makes the drivers simpler and consistent. The following changes are
included:
The brightness attribute only sets and reads the brightness variable in the
backlight_properties structure.
The power attribute only sets and reads the power variable in the
backlight_properties structure.
Any framebuffer blanking events change a variable fb_blank in the
backlight_properties structure.
The backlight driver has only two functions to implement. One function is
called when any of the above properties change (to update the backlight
brightness), the second is called to return the current backlight brightness
value. A new attribute "actual_brightness" is added to return this brightness
as determined by the driver having combined all the above factors (and any
driver/device specific factors).
Additionally, the backlight core takes care of checking the maximum brightness
is not exceeded and of turning off the backlight before device removal.
The corgi backlight driver is updated to reflect these changes.
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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It is very common to hash a dentry and then to call lookup. If we take fs
specific hash functions into account the full hash logic can get ugly.
Further full_name_hash as an inline function is almost 100 bytes on x86 so
having a non-inline choice in some cases can measurably decrease code size.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Simplifies the code, reduces the need for 4 pid hash tables, and makes the
code more capable.
In the discussions I had with Oleg it was felt that to a large extent the
cleanup itself justified the work. With struct pid being dynamically
allocated meant we could create the hash table entry when the pid was
allocated and free the hash table entry when the pid was freed. Instead of
playing with the hash lists when ever a process would attach or detach to a
process.
For myself the fact that it gave what my previous task_ref patch gave for free
with simpler code was a big win. The problem is that if you hold a reference
to struct task_struct you lock in 10K of low memory. If you do that in a user
controllable way like /proc does, with an unprivileged but hostile user space
application with typical resource limits of 1000 fds and 100 processes I can
trigger the OOM killer by consuming all of low memory with task structs, on a
machine wight 1GB of low memory.
If I instead hold a reference to struct pid which holds a pointer to my
task_struct, I don't suffer from that problem because struct pid is 2 orders
of magnitude smaller. In fact struct pid is small enough that most other
kernel data structures dwarf it, so simply limiting the number of referring
data structures is enough to prevent exhaustion of low memory.
This splits the current struct pid into two structures, struct pid and struct
pid_link, and reduces our number of hash tables from PIDTYPE_MAX to just one.
struct pid_link is the per process linkage into the hash tables and lives in
struct task_struct. struct pid is given an indepedent lifetime, and holds
pointers to each of the pid types.
The independent life of struct pid simplifies attach_pid, and detach_pid,
because we are always manipulating the list of pids and not the hash table.
In addition in giving struct pid an indpendent life it makes the concept much
more powerful.
Kernel data structures can now embed a struct pid * instead of a pid_t and
not suffer from pid wrap around problems or from keeping unnecessarily
large amounts of memory allocated.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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A big problem with rcu protected data structures that are also reference
counted is that you must jump through several hoops to increase the reference
count. I think someone finally implemented atomic_inc_not_zero(&count) to
automate the common case. Unfortunately this means you must special case the
rcu access case.
When data structures are only visible via rcu in a manner that is not
determined by the reference count on the object (i.e. tasks are visible until
their zombies are reaped) there is a much simpler technique we can employ.
Simply delaying the decrement of the reference count until the rcu interval is
over.
What that means is that the proc code that looks up a task and later
wants to sleep can now do:
rcu_read_lock();
task = find_task_by_pid(some_pid);
if (task) {
get_task_struct(task);
}
rcu_read_unlock();
The effect on the rest of the kernel is that put_task_struct becomes cheaper
and immediate, and in the case where the task has been reaped it frees the
task immediate instead of unnecessarily waiting an until the rcu interval is
over.
Cleanup of task_struct does not happen when its reference count drops to
zero, instead cleanup happens when release_task is called. Tasks can only
be looked up via rcu before release_task is called. All rcu protected
members of task_struct are freed by release_task.
Therefore we can move call_rcu from put_task_struct into release_task. And
we can modify release_task to not immediately release the reference count
but instead have it call put_task_struct from the function it gives to
call_rcu.
The end result:
- get_task_struct is safe in an rcu context where we have just looked
up the task.
- put_task_struct() simplifies into its old pre rcu self.
This reorganization also makes put_task_struct uncallable from modules as
it is not exported but it does not appear to be called from any modules so
this should not be an issue, and is trivially fixed.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This just got nuked in mainline. Bring it back because Eric's patches use it.
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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To increase the strength of SCHED_BATCH as a scheduling hint we can
activate batch tasks on the expired array since by definition they are
latency insensitive tasks.
Signed-off-by: Con Kolivas <kernel@kolivas.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The activated flag in task_struct is used to track different sleep types and
its usage is somewhat obfuscated. Convert the variable to an enum with more
descriptive names without altering the function.
Signed-off-by: Con Kolivas <kernel@kolivas.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Currently, count_active_tasks() calls both nr_running() &
nr_interruptible(). Each of these functions does a "for_each_cpu" & reads
values from the runqueue of each cpu. Although this is not a lot of
instructions, each runqueue may be located on different node. Depending on
the architecture, a unique TLB entry may be required to access each
runqueue.
Since there may be more runqueues than cpu TLB entries, a scan of all
runqueues can trash the TLB. Each memory reference incurs a TLB miss &
refill.
In addition, the runqueue cacheline that contains nr_running &
nr_uninterruptible may be evicted from the cache between the two passes.
This causes unnecessary cache misses.
Combining nr_running() & nr_interruptible() into a single function
substantially reduces the TLB & cache misses on large systems. This should
have no measureable effect on smaller systems.
On a 128p IA64 system running a memory stress workload, the new function
reduced the overhead of calc_load() from 605 usec/call to 324 usec/call.
Signed-off-by: Jack Steiner <steiner@sgi.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The removal of the data field in the hrtimer structure enforces the
embedding of the timer into another data structure. nanosleep now uses a
private implementation of the most common used timer callback function
(simple task wakeup).
In order to avoid the reimplentation of such functionality all over the
place a generic hrtimer_sleeper functionality is created.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Add an LED trigger for IDE disk activity to the ide-disk driver.
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Acked-by: Bartlomiej Zolnierkiewicz <B.Zolnierkiewicz@elka.pw.edu.pl>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Add support for LED triggers to the LED subsystem. "Triggers" are events
which change the state of an LED. Two kinds of trigger are available, simple
ones which can be added to exising code with minimum disruption and complex
ones for implementing new or more complex functionality.
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Add the foundations of a new LEDs subsystem. This patch adds a class which
presents LED devices within sysfs and allows their brightness to be
controlled.
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Add TIOCL_GETKMSGREDIRECT needed by the userland suspend tool to get the
current value of kmsg_redirect from the kernel so that it can save it and
restore it after resume.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@suse.cz>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Remove the recently-added LINUX_FADV_ASYNC_WRITE and LINUX_FADV_WRITE_WAIT
fadvise() additions, do it in a new sys_sync_file_range() syscall instead.
Reasons:
- It's more flexible. Things which would require two or three syscalls with
fadvise() can be done in a single syscall.
- Using fadvise() in this manner is something not covered by POSIX.
The patch wires up the syscall for x86.
The sycall is implemented in the new fs/sync.c. The intention is that we can
move sys_fsync(), sys_fdatasync() and perhaps sys_sync() into there later.
Documentation for the syscall is in fs/sync.c.
A test app (sync_file_range.c) is in
http://www.zip.com.au/~akpm/linux/patches/stuff/ext3-tools.tar.gz.
The available-to-GPL-modules do_sync_file_range() is for knfsd: "A COMMIT can
say NFS_DATA_SYNC or NFS_FILE_SYNC. I can skip the ->fsync call for
NFS_DATA_SYNC which is hopefully the more common."
Note: the `async' writeout mode SYNC_FILE_RANGE_WRITE will turn synchronous if
the queue is congested. This is trivial to fix: add a new flag bit, set
wbc->nonblocking. But I'm not sure that we want to expose implementation
details down to that level.
Note: it's notable that we can sync an fd which wasn't opened for writing.
Same with fsync() and fdatasync()).
Note: the code takes some care to handle attempts to sync file contents
outside the 16TB offset on 32-bit machines. It makes such attempts appear to
succeed, for best 32-bit/64-bit compatibility. Perhaps it should make such
requests fail...
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: Ulrich Drepper <drepper@redhat.com>
Cc: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Matt Domsch noticed a startup race with the IPMI kernel thread, it was
possible (though extraordinarly unlikely) that a message could come in
before the upper layer was ready to handle it. This patch splits the
startup processing of an IPMI interface into two parts, one to get ready
and one to actually start the processes to receive messages from the
interface.
[akpm@osdl.org: cleanups]
Signed-off-by: Corey Minyard <minyard@acm.org>
Cc: Matt Domsch <Matt_Domsch@dell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Make baby-simple the code for /proc/devices. Based on the proven design
for /proc/interrupts.
This also fixes the early-termination regression 2.6.16 introduced, as
demonstrated by:
# dd if=/proc/devices bs=1
Character devices:
1 mem
27+0 records in
27+0 records out
This should also work (but is untested) when /proc/devices >4096 bytes,
which I believe is what the original 2.6.16 rewrite fixed.
[akpm@osdl.org: cleanups, simplifications]
Signed-off-by: Joe Korty <joe.korty@ccur.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Commit a4a6198b80cf82eb8160603c98da218d1bd5e104:
[PATCH] tvec_bases too large for per-cpu data
introduced "struct tvec_t_base_s boot_tvec_bases" which is visible at
compile time. This means we can kill __init_timer_base and move
timer_base_s's content into tvec_t_base_s.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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find_trylock_page() is an odd interface in that it doesn't take a reference
like the others. Now that XFS no longer uses it, and its last remaining
caller actually wants an elevated refcount, opencode that callsite and
schedule find_trylock_page() for removal.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Fix migrate_pages_to() definition.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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- chips/sharp.c: make two needlessly global functions static
- move some declarations to a header file where they belong to
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Acked-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Semaphore to mutex conversion.
The conversion was generated via scripts, and the result was validated
automatically via a script as well.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Previously we added NET_IP_ALIGN so an architecture can override the
padding done to align headers. The next step is to allow the skb
headroom to be overridden.
We currently always reserve 16 bytes to grow into, meaning all DMAs
start 16 bytes into a cacheline. On ppc64 we really want DMA writes to
start on a cacheline boundary, so we increase that headroom to one
cacheline.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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master.kernel.org:/pub/scm/linux/kernel/git/jgarzik/libata-dev
* 'upstream-linus' of master.kernel.org:/pub/scm/linux/kernel/git/jgarzik/libata-dev:
[PATCH] sata_mv: three bug fixes
[PATCH] libata: ata_dev_init_params() fixes
[PATCH] libata: Fix interesting use of "extern" and also some bracketing
[PATCH] libata: Simplex and other mode filtering logic
[PATCH] libata - ATA is both ATA and CFA
[PATCH] libata: Add ->set_mode hook for odd drivers
[PATCH] libata: BMDMA handling updates
[PATCH] libata: kill trailing whitespace
[PATCH] libata: add FIXME above ata_dev_xfermask()
[PATCH] libata: cosmetic changes in ata_bus_softreset()
[PATCH] libata: kill E.D.D.
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This enables the caller to migrate pages from one address space page
cache to another. In buzz word marketing, you can do zero-copy file
copies!
Signed-off-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This adds support for the sys_splice system call. Using a pipe as a
transport, it can connect to files or sockets (latter as output only).
From the splice.c comments:
"splice": joining two ropes together by interweaving their strands.
This is the "extended pipe" functionality, where a pipe is used as
an arbitrary in-memory buffer. Think of a pipe as a small kernel
buffer that you can use to transfer data from one end to the other.
The traditional unix read/write is extended with a "splice()" operation
that transfers data buffers to or from a pipe buffer.
Named by Larry McVoy, original implementation from Linus, extended by
Jens to support splicing to files and fixing the initial implementation
bugs.
Signed-off-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Add a field to the host_set called 'flags' (was host_set_flags changed
to suit Jeff)
Add a simplex_claimed field so we can remember who owns the DMA channel
Add a ->mode_filter() hook to allow drivers to filter modes
Add docs for mode_filter and set_mode
Filter according to simplex state
Filter cable in core
This provides the needed framework to support all the mode rules found
in the PATA world. The simplex filter deals with 'to spec' simplex DMA
systems found in older chips. The cable filter avoids duplicating the
same rules in each chip driver with PATA. Finally the mode filter is
neccessary because drive/chip combinations have errata that forbid
certain modes with some drives or types of ATA object.
Drive speed setup remains per channel for now and the filters now use
the framework Tejun put into place which cleans them up a lot from the
older libata-pata patches.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
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Some hardware doesn't want the usual mode setup logic running. This
allows the hardware driver to replace it for special cases in the least
invasive way possible.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
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This is the minimal patch set to enable the current code to be used with
a controller following SFF (ie any PATA and early SATA controllers)
safely without crashes if there is no BMDMA area or if BMDMA is not
assigned by the BIOS for some reason.
Simplex status is recorded but not acted upon in this change, this isn't
a problem with the current drivers as none of them are for simplex
hardware. A following diff will deal with that.
The flags in the probe structure remain ->host_set_flags although Jeff
asked me to rename them, simply because the rename would break the usual
Linux rules that old code should break when there are changes. not
compile and run and then blow up/eat your computer/etc. Renaming this
later is a trivial exercise once a better name is chosen.
Signed-off-by: Jeff Garzik <jeff@garzik.org>
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On a allyesconfig'ured kernel:
Size Uses Wasted Name and definition
===== ==== ====== ================================================
95 162 12075 netif_wake_queue include/linux/netdevice.h
129 86 9265 dev_kfree_skb_any include/linux/netdevice.h
127 56 5885 netif_device_attach include/linux/netdevice.h
73 86 4505 dev_kfree_skb_irq include/linux/netdevice.h
46 60 1534 netif_device_detach include/linux/netdevice.h
119 16 1485 __netif_rx_schedule include/linux/netdevice.h
143 5 492 netif_rx_schedule include/linux/netdevice.h
81 7 366 netif_schedule include/linux/netdevice.h
netif_wake_queue is big because __netif_schedule is a big inline:
static inline void __netif_schedule(struct net_device *dev)
{
if (!test_and_set_bit(__LINK_STATE_SCHED, &dev->state)) {
unsigned long flags;
struct softnet_data *sd;
local_irq_save(flags);
sd = &__get_cpu_var(softnet_data);
dev->next_sched = sd->output_queue;
sd->output_queue = dev;
raise_softirq_irqoff(NET_TX_SOFTIRQ);
local_irq_restore(flags);
}
}
static inline void netif_wake_queue(struct net_device *dev)
{
#ifdef CONFIG_NETPOLL_TRAP
if (netpoll_trap())
return;
#endif
if (test_and_clear_bit(__LINK_STATE_XOFF, &dev->state))
__netif_schedule(dev);
}
By de-inlining __netif_schedule we are saving a lot of text
at each callsite of netif_wake_queue and netif_schedule.
__netif_rx_schedule is also big, and it makes more sense to keep
both of them out of line.
Patch also deinlines dev_kfree_skb_any. We can deinline dev_kfree_skb_irq
instead... oh well.
netif_device_attach/detach are not hot paths, we can deinline them too.
Signed-off-by: Denis Vlasenko <vda@ilport.com.ua>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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* git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc: (67 commits)
[PATCH] powerpc: Remove oprofile spinlock backtrace code
[PATCH] powerpc: Add oprofile calltrace support to all powerpc cpus
[PATCH] powerpc: Add oprofile calltrace support
[PATCH] for_each_possible_cpu: ppc
[PATCH] for_each_possible_cpu: powerpc
[PATCH] lock PTE before updating it in 440/BookE page fault handler
[PATCH] powerpc: Kill _machine and hard-coded platform numbers
ppc: Fix compile error in arch/ppc/lib/strcase.c
[PATCH] git-powerpc: WARN was a dumb idea
[PATCH] powerpc: a couple of trivial compile warning fixes
powerpc: remove OCP references
powerpc: Make uImage default build output for MPC8540 ADS
powerpc: move math-emu over to arch/powerpc
powerpc: use memparse() for mem= command line parsing
ppc: fix strncasecmp prototype
[PATCH] powerpc: make ISA floppies work again
[PATCH] powerpc: Fix some initcall return values
[PATCH] powerpc: Workaround for pSeries RTAS bug
[PATCH] spufs: fix __init/__exit annotations
[PATCH] powerpc: add hvc backend for rtas
...
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Move 'tsk->sighand = NULL' from cleanup_sighand() to __exit_signal(). This
makes the exit path more understandable and allows us to do
cleanup_sighand() outside of ->siglock protected section.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch kills PIDTYPE_TGID pid_type thus saving one hash table in
kernel/pid.c and speeding up subthreads create/destroy a bit. It is also a
preparation for the further tref/pids rework.
This patch adds 'struct list_head thread_group' to 'struct task_struct'
instead.
We don't detach group leader from PIDTYPE_PID namespace until another
thread inherits it's ->pid == ->tgid, so we are safe wrt premature
free_pidmap(->tgid) call.
Currently there are no users of find_task_by_pid_type(PIDTYPE_TGID).
Should the need arise, we can use find_task_by_pid()->group_leader.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-By: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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__exit_signal() is private to release_task() now. I think it is better to
make it static in kernel/exit.c and export flush_sigqueue() instead - this
function is much more simple and straightforward.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Cosmetic, rename __exit_sighand to cleanup_sighand and move it close to
copy_sighand().
This matches copy_signal/cleanup_signal naming, and I think it is easier to
follow.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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__exit_signal() does important cleanups atomically under ->siglock. It is
also called from copy_process's error path. This is not good, for example we
can't move __unhash_process() under ->siglock for that reason.
We should not mix these 2 paths, just look at ugly 'if (p->sighand)' under
'bad_fork_cleanup_sighand:' label. For copy_process() case it is sufficient
to just backout copy_signal(), nothing more.
Again, nobody can see this task yet. For CLONE_THREAD case we just decrement
signal->count, otherwise nobody can see this ->signal and we can free it
lockless.
This patch assumes it is safe to do exit_thread_group_keys() without
tasklist_lock.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The only caller of exit_sighand(tsk) is copy_process's error path. We can
call __exit_sighand() directly and kill exit_sighand().
This 'tsk' was not yet registered in pid_hash[] or init_task.tasks, it has no
external references, nobody can see it, and
IF (clone_flags & CLONE_SIGHAND)
At least 'current' has a reference to ->sighand, this
means atomic_dec_and_test(sighand->count) can't be true.
ELSE
Nobody can see this ->sighand, this means we can free it
without any locking.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Add lock_task_sighand() helper and converts group_send_sig_info() to use
it. Hopefully we will have more users soon.
This patch also removes '!sighand->count' and '!p->usage' checks, I think
they both are bogus, racy and unneeded (but probably it makes sense to
restore them as BUG_ON()s).
->sighand is cleared and it's ->count is decremented in release_task() with
sighand->siglock held, so it is a bug to have '!p->usage || !->count' after
we already locked and verified it is the same. On the other hand, an
already dead task without ->sighand can have a non-zero ->usage due to
ptrace, for example.
If we read the stale value of ->sighand we must see the change after
spin_lock(), because that change was done while holding that same old
->sighand.siglock.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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This patch borrows a clever Hugh's 'struct anon_vma' trick.
Without tasklist_lock held we can't trust task->sighand until we locked it
and re-checked that it is still the same.
But this means we don't need to defer 'kmem_cache_free(sighand)'. We can
return the memory to slab immediately, all we need is to be sure that
sighand->siglock can't dissapear inside rcu protected section.
To do so we need to initialize ->siglock inside ctor function,
SLAB_DESTROY_BY_RCU does the rest.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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daemonize() calls set_special_pids(1,1), while init and kernel threads spawned
from init/main.c:init() run with 0,0 special pids. This patch changes
INIT_SIGNALS() so that that they run with ->pgrp == ->session == 1 also. This
patch relies on fact that swapper's pid == 1.
Now we have no hashed zero pids in pid_hash[].
User-space visibible change is that now /sbin/init runs with (1,1) special
pids and becomes a session leader.
Quoting Eric W. Biederman:
>
> daemonize consuming pids (1,1) then consumes pgrp 1. So that when
> /sbin/init calls setsid() it thinks /sbin/init is a process group
> leader and setsid() fails. So /sbin/init wants pgrp 1 session 1
> but doesn't get it. I am pretty certain daemonize did not exist so
> /sbin/init got pgrp 1 session 1 in 2.4.
>
> That is the bug that is being fixed.
>
> This patch takes things one step farther and essentially calls
> setsid() for pid == 1 before init is execed. That is new behavior
> but it cleans up the kernel as we now do not need to support the
> case of a process without a process group or a session.
>
> The only process that could have possibly cared was /sbin/init
> and it already calls setsid() because it doesn't want that.
>
> If this was going to break anything noticeable the change in behavior
> from 2.4 to 2.6 would have already done that.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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fork_idle() does unhash_process() just after copy_process(). Contrary,
boot_cpu's idle thread explicitely registers itself for each pid_type with nr
= 0.
copy_process() already checks p->pid != 0 before process_counts++, I think we
can just skip attach_pid() calls and job control inits for idle threads and
kill unhash_process(). We don't need to cleanup ->proc_dentry in fork_idle()
because with this patch idle threads are never hashed in
kernel/pid.c:pid_hash[].
We don't need to hash pid == 0 in pidmap_init(). free_pidmap() is never
called with pid == 0 arg, so it will never be reused. So it is still possible
to use pid == 0 in any PIDTYPE_xxx namespace from kernel/pid.c's POV.
However with this patch we don't hash pid == 0 for PIDTYPE_PID case. We still
have have PIDTYPE_PGID/PIDTYPE_SID entries with pid == 0: /sbin/init and
kernel threads which don't call daemonize().
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Both SET_LINKS() and SET_LINKS/REMOVE_LINKS() have exactly one caller, and
these callers already check thread_group_leader().
This patch kills theese macros, they mix two different things: setting
process's parent and registering it in init_task.tasks list. Callers are
updated to do these actions by hand.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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add_parent(p, parent) is always called with parent == p->parent, and it makes
no sense to do it differently. This patch removes this argument.
No changes in affected .o files.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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switch_exec_pids is only called from de_thread by way of exec, and it is
only called when we are exec'ing from a non thread group leader.
Currently switch_exec_pids gives the leader the pid of the thread and
unhashes and rehashes all of the process groups. The leader is already in
the EXIT_DEAD state so no one cares about it's pids. The only concern for
the leader is that __unhash_process called from release_task will function
correctly. If we don't touch the leader at all we know that
__unhash_process will work fine so there is no need to touch the leader.
For the task becomming the thread group leader, we just need to give it the
pid of the old thread group leader, add it to the task list, and attach it
to the session and the process group of the thread group.
Currently de_thread is also adding the task to the task list which is just
silly.
Currently the only leader of __detach_pid besides detach_pid is
switch_exec_pids because of the ugly extra work that was being
performed.
So this patch removes switch_exec_pids because it is doing too much, it is
creating an unnecessary special case in pid.c, duing work duplicated in
de_thread, and generally obscuring what it is going on.
The necessary work is added to de_thread, and it seems to be a little
clearer there what is going on.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Kirill Korotaev <dev@sw.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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The kill_sl function doesn't exist in the kernel so a prototype is completely
unnecessary.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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