now type sema_t is a structure which can be put in a shared memory area,
and multiple processes can operate it concurrently.
User can either use mmap(MAP_SHARED) + sem_init(pshared=1) or use sem_open()
to initialize a shared semaphore.
Named semaphore uses file system and is located in /tmp directory, and its
file name is prefixed with 'SEMD', so now it is chroot or jail friendly.
In simplist cases, both for named and un-named semaphore, userland code
does not have to enter kernel to reduce/increase semaphore's count.
The semaphore is designed to be crash-safe, it means even if an application
is crashed in the middle of operating semaphore, the semaphore state is
still safely recovered by later use, there is no waiter counter maintained
by userland code.
The main semaphore code is in libc and libthr only has some necessary stubs,
this makes it possible that a non-threaded application can use semaphore
without linking to thread library.
Old semaphore implementation is kept libc to maintain binary compatibility.
The kernel ksem API is no longer used in the new implemenation.
Discussed on: threads@
it from the build.
If you are using the FTP daemon, please consider using the port ftp/tnftpd
which is the same FTP server, but newer and might have more/better
functionality.
This results in us providing only one ftp daemon by default.
Reviewed by: bz
Approved by: imp (mentor, implicit)
MFC after: 3 days
Silence from: obrien
vnet.h, we now use jails (rather than vimages) as the abstraction
for virtualization management, and what remained was specific to
virtual network stacks. Minor cleanups are done in the process,
and comments updated to reflect these changes.
Reviewed by: bz
Approved by: re (vimage blanket)
preparation for 8.0-RELEASE. Add the previous version of those
libraries to ObsoleteFiles.inc and bump __FreeBSD_Version.
Reviewed by: kib
Approved by: re (rwatson)
(DPCPU), as suggested by Peter Wemm, and implement a new per-virtual
network stack memory allocator. Modify vnet to use the allocator
instead of monolithic global container structures (vinet, ...). This
change solves many binary compatibility problems associated with
VIMAGE, and restores ELF symbols for virtualized global variables.
Each virtualized global variable exists as a "reference copy", and also
once per virtual network stack. Virtualized global variables are
tagged at compile-time, placing the in a special linker set, which is
loaded into a contiguous region of kernel memory. Virtualized global
variables in the base kernel are linked as normal, but those in modules
are copied and relocated to a reserved portion of the kernel's vnet
region with the help of a the kernel linker.
Virtualized global variables exist in per-vnet memory set up when the
network stack instance is created, and are initialized statically from
the reference copy. Run-time access occurs via an accessor macro, which
converts from the current vnet and requested symbol to a per-vnet
address. When "options VIMAGE" is not compiled into the kernel, normal
global ELF symbols will be used instead and indirection is avoided.
This change restores static initialization for network stack global
variables, restores support for non-global symbols and types, eliminates
the need for many subsystem constructors, eliminates large per-subsystem
structures that caused many binary compatibility issues both for
monitoring applications (netstat) and kernel modules, removes the
per-function INIT_VNET_*() macros throughout the stack, eliminates the
need for vnet_symmap ksym(2) munging, and eliminates duplicate
definitions of virtualized globals under VIMAGE_GLOBALS.
Bump __FreeBSD_version and update UPDATING.
Portions submitted by: bz
Reviewed by: bz, zec
Discussed with: gnn, jamie, jeff, jhb, julian, sam
Suggested by: peter
Approved by: re (kensmith)
Clists were originally used by the TTY layer as a text buffer interface.
The advantage of clists were that it would allocate a small set of
additional buffers that could be shared between TTYs when needed. In
the modern days we can just allocate some more KBs of memory to keep the
TTYs satisfied. The global cfreelist also requires synchronisation,
which may not be useful when trying to improve scalability.
The MPSAFE TTY layer uses its own text buffers (ttyinq and ttyoutq). We
had a small amount of drivers in the tree that still uses clists, like
the old USB stack and some keyboard drivers. With the old USB stack gone
and the keyboard drivers changed to use a circular buffer, we can safely
remove clists from the kernel.
Some time ago Tom Rhodes sent me an email that he was willing to perform
various cleanups to the window(1) source code. After some discussion, we
both decided the best thing to do, was to move window(1) to the ports
tree. The application isn't used a lot nowadays, mainly because it has
been superseeded by screen, tmux, etc.
A couple of hours ago Tom committed window(1) to ports (misc/window), so
I'm removing it from the tree. I don't think people will really miss it,
but I'm describing the change in UPDATING anyway.
Discussed with: trhodes, pav, kib
Approved by: re
Last year I added SLIST_REMOVE_NEXT and STAILQ_REMOVE_NEXT, to remove
entries behind an element in the list, using O(1) time. I recently
discovered NetBSD also has a similar macro, called SLIST_REMOVE_AFTER.
In my opinion this approach is a lot better:
- It doesn't have the unused first argument of the list pointer. I added
this, mainly because OpenBSD also had it.
- The _AFTER suffix makes a lot more sense, because it is related to
SLIST_INSERT_AFTER. _NEXT is only used to iterate through the list.
The reason why I want to rename this now, is to make sure we don't
release a major version with the badly named macros.
Not only did these two drivers depend on IFF_NEEDSGIANT, they were
broken 7 months ago during the MPSAFE TTY import. if_ppp(4) has been
replaced by ppp(8). There is no replacement for if_sl(4).
If we see regressions in for example the ports tree, we should just use
__FreeBSD_version 800045 to check whether if_ppp(4) and if_sl(4) are
present. Version 800045 is used to denote the import of MPSAFE TTY.
Discussed with: rwatson, but also rwatson's IFF_NEEDSGIANT emails on the
lists.
driver in Linux 2.6. uscanner was just a simple wrapper around a fifo and
contained no logic, the default interface is now libusb (supported by sane).
Reviewed by: HPS
ports tree so that programs use libusb from the base by default. Thanks to
Stanislav Sedov for sorting out the ports build.
Bump __FreeBSD_version to 800069
Help and testing by: stas
The function pow() in libmp(3) clashes with pow(3) in libm. We could
rename this single function, but we can just take the same approach as
the Solaris folks did, which is to prefix all function names with mp_.
libmp(3) isn't really popular nowadays. I suspect not a single
application in ports depends on it. There's still a chance, so I've
increased the SHLIB_MAJOR and __FreeBSD_version.
Reviewed by: deischen, rdivacky
