Currently, when the ring buffer drops events, it does not record
the fact that it did so. It does inform the writer that the event
was dropped by returning a NULL event, but it does not put in any
place holder where the event was dropped.
This is not a trivial thing to add because the ring buffer mostly
runs in overwrite (flight recorder) mode. That is, when the ring
buffer is full, new data will overwrite old data.
In a produce/consumer mode, where new data is simply dropped when
the ring buffer is full, it is trivial to add the placeholder
for dropped events. When there's more room to write new data, then
a special event can be added to notify the reader about the dropped
events.
But in overwrite mode, any new write can overwrite events. A place
holder can not be inserted into the ring buffer since there never
may be room. A reader could also come in at anytime and miss the
placeholder.
Luckily, the way the ring buffer works, the read side can find out
if events were lost or not, and how many events. Everytime a write
takes place, if it overwrites the header page (the next read) it
updates a "overrun" variable that keeps track of the number of
lost events. When a reader swaps out a page from the ring buffer,
it can record this number, perfom the swap, and then check to
see if the number changed, and take the diff if it has, which would be
the number of events dropped. This can be stored by the reader
and returned to callers of the reader.
Since the reader page swap will fail if the writer moved the head
page since the time the reader page set up the swap, this gives room
to record the overruns without worrying about races. If the reader
sets up the pages, records the overrun, than performs the swap,
if the swap succeeds, then the overrun variable has not been
updated since the setup before the swap.
For binary readers of the ring buffer, a flag is set in the header
of each sub page (sub buffer) of the ring buffer. This flag is embedded
in the size field of the data on the sub buffer, in the 31st bit (the size
can be 32 or 64 bits depending on the architecture), but only 27
bits needs to be used for the actual size (less actually).
We could add a new field in the sub buffer header to also record the
number of events dropped since the last read, but this will change the
format of the binary ring buffer a bit too much. Perhaps this change can
be made if the information on the number of events dropped is considered
important enough.
Note, the notification of dropped events is only used by consuming reads
or peeking at the ring buffer. Iterating over the ring buffer does not
keep this information because the necessary data is only available when
a page swap is made, and the iterator does not swap out pages.
Cc: Robert Richter <robert.richter@amd.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: "Luis Claudio R. Goncalves" <lclaudio@uudg.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Remove the @refcnt argument, because it has side-effects, and arguments with
side-effects are not skipped by the jump over disabled instrumentation and are
executed even when the tracepoint is disabled.
This was also causing a GPF as found by Randy Dunlap:
Subject: 2.6.33 GP fault only when built with tracing
LKML-Reference: <4BA2B69D.3000309@oracle.com>
Note, the current 2.6.34-rc has a fix for the actual cause of the GPF,
but this fixes one of its triggers.
Tested-by: Randy Dunlap <randy.dunlap@oracle.com>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4BA97FA7.6040406@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (33 commits)
r8169: offical fix for CVE-2009-4537 (overlength frame DMAs)
ipv6: Don't drop cache route entry unless timer actually expired.
tulip: Add missing parens.
r8169: fix broken register writes
pcnet_cs: add new id
bonding: fix broken multicast with round-robin mode
drivers/net: Fix continuation lines
e1000: do not modify tx_queue_len on link speed change
net: ipmr/ip6mr: prevent out-of-bounds vif_table access
ixgbe: Do not run all Diagnostic offline tests when VFs are active
igb: use correct bits to identify if managability is enabled
benet: Fix compile warnnings in drivers/net/benet/be_ethtool.c
net: Add MSG_WAITFORONE flag to recvmmsg
e1000e: do not modify tx_queue_len on link speed change
igbvf: do not modify tx_queue_len on link speed change
ipv4: Restart rt_intern_hash after emergency rebuild (v2)
ipv4: Cleanup struct net dereference in rt_intern_hash
net: fix netlink address dumping in IPv4/IPv6
tulip: Fix null dereference in uli526x_rx_packet()
gianfar: fix undo of reserve()
...
In commit 9df93939b7 ("ext3: Use bitops to read/modify
EXT3_I(inode)->i_state") ext3 changed its internal 'i_state' variable to
use bitops for its state handling. However, unline the same ext4
change, it didn't actually change the name of the field when it changed
the semantics of it.
As a result, an old use of 'i_state' remained in fs/ext3/ialloc.c that
initialized the field to EXT3_STATE_NEW. And that does not work
_at_all_ when we're now working with individually named bits rather than
values that get masked. So the code tried to mark the state to be new,
but in actual fact set the field to EXT3_STATE_JDATA. Which makes no
sense at all, and screws up all the code that checks whether the inode
was newly allocated.
In particular, it made the xattr code unhappy, and caused various random
behavior, like apparently
https://bugzilla.redhat.com/show_bug.cgi?id=577911
So fix the initialization, and rename the field to match ext4 so that we
don't have this happen again.
Cc: James Morris <jmorris@namei.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Daniel J Walsh <dwalsh@redhat.com>
Cc: Eric Paris <eparis@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
CONFIG_SLOW_WORK_PROC was changed to CONFIG_SLOW_WORK_DEBUG, but not in all
instances. Change the remaining instances. This makes the debugfs file
display the time mark and the owner's description again.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add new flag MSG_WAITFORONE for the recvmmsg() syscall.
When this flag is specified for a blocking socket, recvmmsg()
will only block until at least 1 packet is available. The
default behavior is to block until all vlen packets are
available. This flag has no effect on non-blocking sockets
or when used in combination with MSG_DONTWAIT.
Signed-off-by: Brandon L Black <blblack@gmail.com>
Acked-by: Ulrich Drepper <drepper@redhat.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6:
x86/PCI: truncate _CRS windows with _LEN > _MAX - _MIN + 1
x86/PCI: for host bridge address space collisions, show conflicting resource
frv/PCI: remove redundant warnings
x86/PCI: remove redundant warnings
PCI: don't say we claimed a resource if we failed
PCI quirk: Disable MSI on VIA K8T890 systems
PCI quirk: RS780/RS880: work around missing MSI initialization
PCI quirk: only apply CX700 PCI bus parking quirk if external VT6212L is present
PCI: complain about devices that seem to be broken
PCI: print resources consistently with %pR
PCI: make disabled window printk style match the enabled ones
PCI: break out primary/secondary/subordinate for readability
PCI: for address space collisions, show conflicting resource
resources: add interfaces that return conflict information
PCI: cleanup error return for pcix get and set mmrbc functions
PCI: fix access of PCI_X_CMD by pcix get and set mmrbc functions
PCI: kill off pci_register_set_vga_state() symbol export.
PCI: fix return value from pcix_get_max_mmrbc()
* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
time: Fix accumulation bug triggered by long delay.
posix-cpu-timers: Reset expire cache when no timer is running
timer stats: Fix del_timer_sync() and try_to_del_timer_sync()
clockevents: Sanitize min_delta_ns adjustment and prevent overflows
The order of the IPv6 raw table is currently reversed, that makes impossible
to use the NOTRACK target in IPv6: for example if someone enters
ip6tables -t raw -A PREROUTING -p tcp --dport 80 -j NOTRACK
and if we receive fragmented packets then the first fragment will be
untracked and thus skip nf_ct_frag6_gather (and conntrack), while all
subsequent fragments enter nf_ct_frag6_gather and reassembly will never
successfully be finished.
Singed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Patrick McHardy <kaber@trash.net>
* 'bugfixes' of git://git.linux-nfs.org/projects/trondmy/nfs-2.6:
NFS: don't try to decode GETATTR if DELEGRETURN returned error
sunrpc: handle allocation errors from __rpc_lookup_create()
SUNRPC: Fix the return value of rpc_run_bc_task()
SUNRPC: Fix a use after free bug with the NFSv4.1 backchannel
SUNRPC: Fix a potential memory leak in auth_gss
NFS: Prevent another deadlock in nfs_release_page()
In the extended CSD register the CARD_TYPE is an 8-bit value of which the
upper 6 bits were reserved in JEDEC specifications prior to version 4.4.
In version 4.4 two of the reserved bits were designated for identifying
support for the newly added High-Speed Dual Data Rate. Unfortunately the
mmc_read_ext_csd() function required that the reserved bits be zero
instead of ignoring them as it should.
This patch makes mmc_read_ext_csd() ignore the CARD_TYPE bits that are
reserved or not yet supported. It also stops the function jumping to the
end as though an error occurred, when it is only warns that the CARD_TYPE
bits (that it does interpret) are invalid.
Signed-off-by: Adrian Hunter <adrian.hunter@nokia.com>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 57fe60df ("reiserfs: add atomic addition of selinux attributes
during inode creation") contains a bug that will cause it to oops when
mounting a file system that didn't previously contain extended attributes
on a system using security.* xattrs.
The issue is that while creating the privroot during mount
reiserfs_security_init calls reiserfs_xattr_jcreate_nblocks which
dereferences the xattr root. The xattr root doesn't exist, so we get an
oops.
Addresses http://bugzilla.kernel.org/show_bug.cgi?id=15309
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The dma map fields in the skb_shared_info structure no longer has any users
and can be dropped since it is making the skb_shared_info unecessarily larger.
Running slabtop show that we were using 4K slabs for the skb->head on x86_64 w/
an allocation size of 1522. It turns out that the dma_head and dma_maps array
made skb_shared large enough that we had crossed over the 2k boundary with
standard frames and as such we were using 4k blocks of memory for all skbs.
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
request_resource() and insert_resource() only return success or failure,
which no information about what existing resource conflicted with the
proposed new reservation. This patch adds request_resource_conflict()
and insert_resource_conflict(), which return the conflicting resource.
Callers may use this for better error messages or to adjust the new
resource and retry the request.
Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Commit 45575f5a42 ("ppc64 sys_ipc breakage in 2.6.34-rc2") fixed the
definition of the sys_ipc() helper, but didn't fix the prototype in
<linux/syscalls.h>
Reported-and-tested-by: Andreas Schwab <schwab@linux-m68k.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (38 commits)
ip_gre: include route header_len in max_headroom calculation
if_tunnel.h: add missing ams/byteorder.h include
ipv4: Don't drop redirected route cache entry unless PTMU actually expired
net: suppress lockdep-RCU false positive in FIB trie.
Bluetooth: Fix kernel crash on L2CAP stress tests
Bluetooth: Convert debug files to actually use debugfs instead of sysfs
Bluetooth: Fix potential bad memory access with sysfs files
netfilter: ctnetlink: fix reliable event delivery if message building fails
netlink: fix NETLINK_RECV_NO_ENOBUFS in netlink_set_err()
NET_DMA: free skbs periodically
netlink: fix unaligned access in nla_get_be64()
tcp: Fix tcp_mark_head_lost() with packets == 0
net: ipmr/ip6mr: fix potential out-of-bounds vif_table access
KS8695: update ksp->next_rx_desc_read at the end of rx loop
igb: Add support for 82576 ET2 Quad Port Server Adapter
ixgbevf: Message formatting cleanups
ixgbevf: Shorten up delay timer for watchdog task
ixgbevf: Fix VF Stats accounting after reset
ixgbe: Set IXGBE_RSC_CB(skb)->DMA field to zero after unmapping the address
ixgbe: fix for real_num_tx_queues update issue
...
The ->release_request() callback was designed to allow the transport layer
to do housekeeping after the RPC call is done. It cannot be used to free
the request itself, and doing so leads to a use-after-free bug in
xprt_release().
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
When compiling userspace application which includes
if_tunnel.h and uses GRE_* defines you will get undefined
reference to __cpu_to_be16.
Fix this by adding missing #include <asm/byteorder.h>
Cc: stable@kernel.org
Signed-off-by: Paulius Zaleckas <paulius.zaleckas@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch fixes a bug that allows to lose events when reliable
event delivery mode is used, ie. if NETLINK_BROADCAST_SEND_ERROR
and NETLINK_RECV_NO_ENOBUFS socket options are set.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently, ENOBUFS errors are reported to the socket via
netlink_set_err() even if NETLINK_RECV_NO_ENOBUFS is set. However,
that should not happen. This fixes this problem and it changes the
prototype of netlink_set_err() to return the number of sockets that
have set the NETLINK_RECV_NO_ENOBUFS socket option. This return
value is used in the next patch in these bugfix series.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
