linux.git/drivers/char/mem.c, branch v3.6

powerpc: Disable /dev/port interface on systems without an ISA bridge

2012-07-11T08:22:32+00:00

Some power systems do not have legacy ISA devices. So, /dev/port is not
a valid interface on these systems. User level tools such as kbdrate is
trying to access the device using this interface which is causing the
system crash.

This patch will fix this issue by not creating this interface on these
powerpc systems.

Signed-off-by: Haren Myneni 
Signed-off-by: Benjamin Herrenschmidt

printk - fix compilation for CONFIG_PRINTK=n

2012-05-09T22:51:09+00:00

Reported-by: Randy Dunlap 
Signed-off-by: Kay Sievers 
Signed-off-by: Greg Kroah-Hartman

kmsg: export printk records to the /dev/kmsg interface

2012-05-08T00:03:27+00:00

Support for multiple concurrent readers of /dev/kmsg, with read(),
seek(), poll() support. Output of message sequence numbers, to allow
userspace log consumers to reliably reconnect and reconstruct their
state at any given time. After open("/dev/kmsg"), read() always
returns *all* buffered records. If only future messages should be
read, SEEK_END can be used. In case records get overwritten while
/dev/kmsg is held open, or records get faster overwritten than they
are read, the next read() will return -EPIPE and the current reading
position gets updated to the next available record. The passed
sequence numbers allow the log consumer to calculate the amount of
lost messages.

  [root@mop ~]# cat /dev/kmsg
  5,0,0;Linux version 3.4.0-rc1+ (kay@mop) (gcc version 4.7.0 20120315 ...
  6,159,423091;ACPI: PCI Root Bridge [PCI0] (domain 0000 [bus 00-ff])
  7,160,424069;pci_root PNP0A03:00: host bridge window [io  0x0000-0x0cf7] (ignored)
   SUBSYSTEM=acpi
   DEVICE=+acpi:PNP0A03:00
  6,339,5140900;NET: Registered protocol family 10
  30,340,5690716;udevd[80]: starting version 181
  6,341,6081421;FDC 0 is a S82078B
  6,345,6154686;microcode: CPU0 sig=0x623, pf=0x0, revision=0x0
  7,346,6156968;sr 1:0:0:0: Attached scsi CD-ROM sr0
   SUBSYSTEM=scsi
   DEVICE=+scsi:1:0:0:0
  6,347,6289375;microcode: CPU1 sig=0x623, pf=0x0, revision=0x0

Cc: Karel Zak 
Tested-by: William Douglas 
Signed-off-by: Kay Sievers 
Signed-off-by: Greg Kroah-Hartman

printk: convert byte-buffer to variable-length record buffer

2012-05-07T23:53:02+00:00

- Record-based stream instead of the traditional byte stream
  buffer. All records carry a 64 bit timestamp, the syslog facility
  and priority in the record header.

- Records consume almost the same amount, sometimes less memory than
  the traditional byte stream buffer (if printk_time is enabled). The record
  header is 16 bytes long, plus some padding bytes at the end if needed.
  The byte-stream buffer needed 3 chars for the syslog prefix, 15 char for
  the timestamp and a newline.

- Buffer management is based on message sequence numbers. When records
  need to be discarded, the reading heads move on to the next full
  record. Unlike the byte-stream buffer, no old logged lines get
  truncated or partly overwritten by new ones. Sequence numbers also
  allow consumers of the log stream to get notified if any message in
  the stream they are about to read gets discarded during the time
  of reading.

- Better buffered IO support for KERN_CONT continuation lines, when printk()
  is called multiple times for a single line. The use of KERN_CONT is now
  mandatory to use continuation; a few places in the kernel need trivial fixes
  here. The buffering could possibly be extended to per-cpu variables to allow
  better thread-safety for multiple printk() invocations for a single line.

- Full-featured syslog facility value support. Different facilities
  can tag their messages. All userspace-injected messages enforce a
  facility value > 0 now, to be able to reliably distinguish them from
  the kernel-generated messages. Independent subsystems like a
  baseband processor running its own firmware, or a kernel-related
  userspace process can use their own unique facility values. Multiple
  independent log streams can co-exist that way in the same
  buffer. All share the same global sequence number counter to ensure
  proper ordering (and interleaving) and to allow the consumers of the
  log to reliably correlate the events from different facilities.

Tested-by: William Douglas 
Signed-off-by: Kay Sievers 
Signed-off-by: Greg Kroah-Hartman

switch device_get_devnode() and ->devnode() to umode_t *

2012-01-04T03:54:55+00:00

both callers of device_get_devnode() are only interested in lower 16bits
and nobody tries to return anything wider than 16bit anyway.

Signed-off-by: Al Viro

drivers/char: Add export.h for EXPORT_SYMBOL/THIS_MODULE as required

2011-10-31T23:31:41+00:00

They will need it called out explicitly in the near future due
to a module.h usage cleanup that removes its implicit presence
everywhere.

Signed-off-by: Paul Gortmaker

kmsg: properly support writev to avoid interleaved printk lines fix

2011-04-20T00:00:48+00:00

make `len' size_t, avoid multiple-assignments.

Cc: Kay Sievers 
Cc: Lennart Poettering 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

printk: /dev/kmsg - properly support writev() to avoid interleaved printk() lines

2011-04-19T23:59:58+00:00

printk: /dev/kmsg - properly support writev() to avoid interleaved printk lines

We should avoid calling printk() in a loop, when we pass a single
string to /dev/kmsg with writev().

Cc: Lennart Poettering 
Signed-off-by: Kay Sievers 
Cc: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

drivers/char/mem.c: clean up the code

2011-03-24T02:46:40+00:00

Reduce the lines of code and simplify the logic.

Signed-off-by: Changli Gao 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

vfs: introduce FMODE_UNSIGNED_OFFSET for allowing negative f_pos

2010-10-26T01:18:21+00:00

Now, rw_verify_area() checsk f_pos is negative or not.  And if negative,
returns -EINVAL.

But, some special files as /dev/(k)mem and /proc//mem etc..  has
negative offsets.  And we can't do any access via read/write to the
file(device).

So introduce FMODE_UNSIGNED_OFFSET to allow negative file offsets.

Signed-off-by: Wu Fengguang 
Signed-off-by: KAMEZAWA Hiroyuki 
Cc: Al Viro 
Cc: Heiko Carstens 
Signed-off-by: Andrew Morton 
Signed-off-by: Al Viro