linux.git/ipc/shm.c, branch v2.6.27

ipc: get rid of ipc_lock_down()

2008-07-25T17:53:42+00:00

Remove the ipc_lock_down() routines: they used to call idr_find() locklessly
(given that the ipc ids lock was already held), so they are not needed
anymore.

Signed-off-by: Nadia Derbey 
Acked-by: "Paul E. McKenney" 
Cc: Manfred Spraul 
Cc: Jim Houston 
Cc: Pierre Peiffer 
Acked-by: Rik van Riel 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

hugetlb: modular state for hugetlb page size

2008-07-24T17:47:17+00:00

The goal of this patchset is to support multiple hugetlb page sizes.  This
is achieved by introducing a new struct hstate structure, which
encapsulates the important hugetlb state and constants (eg.  huge page
size, number of huge pages currently allocated, etc).

The hstate structure is then passed around the code which requires these
fields, they will do the right thing regardless of the exact hstate they
are operating on.

This patch adds the hstate structure, with a single global instance of it
(default_hstate), and does the basic work of converting hugetlb to use the
hstate.

Future patches will add more hstate structures to allow for different
hugetlbfs mounts to have different page sizes.

[akpm@linux-foundation.org: coding-style fixes]
Acked-by: Adam Litke 
Acked-by: Nishanth Aravamudan 
Signed-off-by: Andi Kleen 
Signed-off-by: Nick Piggin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

/proc/sysvipc/shm: fix 32-bit truncation of segment sizes

2008-06-13T01:05:41+00:00

sysvipc_shm_proc_show() picks between format strings (based on the
expected maximum length of a SHM segment) in a way that prevents gcc from
performing format checks on the seq_printf() parameters.  This hid two
format errors - shp->shm_segsz and shp->shm_nattach are both unsigned
long, but were being printed as unsigned int and signed int respectively.
This leads to 32-bit truncation of SHM segment sizes reported in
/proc/sysvipc/shm.  (And for nattach, but that's less of a problem for
most users).

This patch makes the format string directly visible to gcc's format
specifier checker, and fixes the two broken format specifiers.

Signed-off-by: Paul Menage 
Cc: Nadia Derbey 
Cc: Manfred Spraul 
Cc: Pierre Peiffer 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

shm: Remove silly double assignment

2008-06-10T14:58:00+00:00

Found a silly double assignment of err is do_shmat.  Silly, but good to
clean up the useless code.

Signed-off-by: Neil Horman 
Signed-off-by: Linus Torvalds

IPC: consolidate all xxxctl_down() functions

2008-04-29T15:06:14+00:00

semctl_down(), msgctl_down() and shmctl_down() are used to handle the same set
of commands for each kind of IPC.  They all start to do the same job (they
retrieve the ipc and do some permission checks) before handling the commands
on their own.

This patch proposes to consolidate this by moving these same pieces of code
into one common function called ipcctl_pre_down().

It simplifies a little these xxxctl_down() functions and increases a little
the maintainability.

Signed-off-by: Pierre Peiffer 
Acked-by: Serge Hallyn 
Cc: Nadia Derbey 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

IPC: introduce ipc_update_perm()

2008-04-29T15:06:13+00:00

The IPC_SET command performs the same permission setting for all IPCs.  This
patch introduces a common ipc_update_perm() function to update these
permissions and makes use of it for all IPCs.

Signed-off-by: Pierre Peiffer 
Acked-by: Serge Hallyn 
Cc: Nadia Derbey 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

IPC: get rid of the use *_setbuf structure.

2008-04-29T15:06:13+00:00

All IPCs make use of an intermetiate *_setbuf structure to handle the IPC_SET
command.  This is not really needed and, moreover, it complicates a little bit
the code.

This patch gets rid of the use of it and uses directly the semid64_ds/
msgid64_ds/shmid64_ds structure.

In addition of removing one struture declaration, it also simplifies and
improves a little bit the common 64-bits path.

Signed-off-by: Pierre Peiffer 
Acked-by: Serge Hallyn 
Cc: Nadia Derbey 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

IPC/shared memory: introduce shmctl_down

2008-04-29T15:06:13+00:00

Currently, the way the different commands are handled in sys_shmctl introduces
some duplicated code.

This patch introduces the shmctl_down function to handle all the commands
requiring the rwmutex to be taken in write mode (ie IPC_SET and IPC_RMID for
now).  It is the equivalent function of semctl_down for shared memory.

This removes some duplicated code for handling these both commands and
harmonizes the way they are handled among all IPCs.

Signed-off-by: Pierre Peiffer 
Acked-by: Serge Hallyn 
Cc: Nadia Derbey 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

IPC: use ipc_buildid() directly from ipc_addid()

2008-04-29T15:06:12+00:00

By continuing to consolidate a little the IPC code, each id can be built
directly in ipc_addid() instead of having it built from each callers of
ipc_addid()

And I also remove shm_addid() in order to have, as much as possible, the
same code for shm/sem/msg.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Pierre Peiffer 
Cc: Nadia Derbey 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mempolicy: rework mempolicy Reference Counting [yet again]

2008-04-28T15:58:24+00:00

After further discussion with Christoph Lameter, it has become clear that my
earlier attempts to clean up the mempolicy reference counting were a bit of
overkill in some areas, resulting in superflous ref/unref in what are usually
fast paths.  In other areas, further inspection reveals that I botched the
unref for interleave policies.

A separate patch, suitable for upstream/stable trees, fixes up the known
errors in the previous attempt to fix reference counting.

This patch reworks the memory policy referencing counting and, one hopes,
simplifies the code.  Maybe I'll get it right this time.

See the update to the numa_memory_policy.txt document for a discussion of
memory policy reference counting that motivates this patch.

Summary:

Lookup of mempolicy, based on (vma, address) need only add a reference for
shared policy, and we need only unref the policy when finished for shared
policies.  So, this patch backs out all of the unneeded extra reference
counting added by my previous attempt.  It then unrefs only shared policies
when we're finished with them, using the mpol_cond_put() [conditional put]
helper function introduced by this patch.

Note that shmem_swapin() calls read_swap_cache_async() with a dummy vma
containing just the policy.  read_swap_cache_async() can call alloc_page_vma()
multiple times, so we can't let alloc_page_vma() unref the shared policy in
this case.  To avoid this, we make a copy of any non-null shared policy and
remove the MPOL_F_SHARED flag from the copy.  This copy occurs before reading
a page [or multiple pages] from swap, so the overhead should not be an issue
here.

I introduced a new static inline function "mpol_cond_copy()" to copy the
shared policy to an on-stack policy and remove the flags that would require a
conditional free.  The current implementation of mpol_cond_copy() assumes that
the struct mempolicy contains no pointers to dynamically allocated structures
that must be duplicated or reference counted during copy.

Signed-off-by: Lee Schermerhorn 
Cc: Christoph Lameter 
Cc: David Rientjes 
Cc: Mel Gorman 
Cc: Andi Kleen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds