Problem:
selwakeup required calling pfind which would cause lock order
reversals with the allproc_lock and the per-process filedesc lock.
Solution:
Instead of recording the pid of the select()'ing process into the
selinfo structure, actually record a pointer to the thread. To
avoid dereferencing a bad address all the selinfo structures that
are in use by a thread are kept in a list hung off the thread
(protected by sellock). When a selwakeup occurs the selinfo is
removed from that threads list, it is also removed on the way out
of select or poll where the thread will traverse its list removing
all the selinfos from its own list.
Problem:
Previously the PROC_LOCK was used to provide the mutual exclusion
needed to ensure proper locking, this couldn't work because there
was a single condvar used for select and poll and condvars can
only be used with a single mutex.
Solution:
Introduce a global mutex 'sellock' which is used to provide mutual
exclusion when recording events to wait on as well as performing
notification when an event occurs.
Interesting note:
schedlock is required to manipulate the per-thread TDF_SELECT
flag, however if given its own field it would not need schedlock,
also because TDF_SELECT is only manipulated under sellock one
doesn't actually use schedlock for syncronization, only to protect
against corruption.
Proc locks are no longer used in select/poll.
Portions contributed by: davidc
-#if defined(__FreeBSD__) && __FreeBSD_version__ >= 500023
+#if defined(__FreeBSD__) && __FreeBSD_version >= 500023
is a genuine bug -- __FreeBSD_version__ does not exist.
The other one:
-#if (__FreeBSD__ < 5)
+#if (__FreeBSD_version < 500000)
pops out when you cross-compile the code:
__FreeBSD__ is a compiler predefine,
__FreeBSD_version is defined in <sys/param.h> .
Given that in this case (and all others in sys/dev/usb and sys/i4b)
the goal is to adapt to a different kernel interface, and not to
a compiler feature, I believe the correct form is the second one
(in the best case the two are synonyms so the change does not break
anything anyways).
device drivers for bus system with other endinesses than the CPU (using
interfaces compatible to NetBSD):
- bwap16() and bswap32(). These have optimized implementations on some
architectures; for those that don't, there exist generic implementations.
- macros to convert from a certain byte order to host byte order and vice
versa, using a naming scheme like le16toh(), htole16().
These are implemented using the bswap functions.
- stream bus space access functions, which do not perform a byte order
conversion (while the normal access functions would if the bus endianess
differs from the CPU endianess).
htons(), htonl(), ntohs() and ntohl() are implemented using the new
functions above for kernel usage. None of the above interfaces is currently
exported to user land.
Make use of the new functions in a few places where local implementations
of the same functionality existed.
Reviewed by: mike, bde
Tested on alpha by: mike
1/ conditionalise (#if 0) function that is not used.
Unused code left in place for netBSD compatibility.
2/ Recode loop to convince gcc that it does initialise a variable
(use do-while instead of for() so gcc knows that we always go through
at least once. Feel free to check my logic.
Also, add some 'const's to supress warnings. (Submitted back to NetBSD).
The original logs from NetBSD:
----------------------------
revision 1.90
date: 2001/12/03 01:47:12; author: augustss; lines: +4 -4
Handle vendor/product lookup with a common routine.
----------------------------
revision 1.89
date: 2001/12/02 23:25:25; author: augustss; lines: +18 -2
Add a subroutine to search for a vendor/product pair.
----------------------------
Original NetBSD log messages are:
----------------------------
revision 1.23
date: 2001/12/12 15:48:18; author: augustss; lines: +132 -114
Add a scanner quirk for keeping the pipes open between device opening.
Idea from Enami.
----------------------------
revision 1.22
date: 2001/12/03 01:47:13; author: augustss; lines: +8 -16
Handle vendor/product lookup with a common routine.
----------------------------
revision 1.21
date: 2001/12/01 09:42:39; author: enami; lines: +4 -4
Shorten wmesg so that they can be distinguished in ps/top output.
----------------------------
revision 1.12
date: 2001/01/23 14:04:14; author: augustss; lines: +7 -1
Make sure driver attach/detach events are generated in a
consistent manner.
----------------------------
PR:
Submitted by:
Reviewed by:
Approved by:
Obtained from:
MFC after:
From the NetBSD logs:
revision 1.45
date: 2001/11/29 11:07:12; author: augustss; state: Exp; lines: +12 -2
Plug a memory leak in an error case.
----------------------------
revision 1.43
date: 2001/10/19 15:30:25; author: nathanw; state: Exp; lines: +5 -3
Match printers that report their interface as IEEE 1284 in addition to
bidirectional.
to fix their code.
ata stuff:
Change name of ar_attach to not colide with existing ar_attach in if_ar.c.
usb stuff:
Create a dummy function to satisfy a call to it when in DEBUG mode.
uhub.c: revision 1.37
usb.4: revision 1.30
usb.c: revision 1.38
usb.h: revision 1.40
usb_port.h: revision 1.21
usb_subr.c: revision 1.65
usbdi.h: revision 1.40
Split the attach/detach events up into device, driver and controller
attach and detach events.
The commit message from NetBSD was:
date: 2000/02/02 07:34:00; author: augustss; state: Exp;
Change the USB event mechanism to include more information
about devices and drivers. Partly from FreeBSD.
Also rework usbd to take these new event types into account.
usb.c: revision 1.39
revision 1.39
date: 2000/02/22 11:30:56; author: augustss; lines: +7 -1
Prepare a little for having USB interrupt processing done
outside the hard interrupt level (in a thread or a softintr).
No real soft processing done yet.
usb.c: revision 1.41
revision 1.41
date: 2000/03/16 00:46:38; author: augustss; lines: +2 -2
Make the USB event queue longer. Mine overflows before the
(user-land) event handler has started. But then I have
about 25 devices connected. :)
