Il 15/03/2012 22:00, Michael Tokarev ha scritto:
> This is cleanup/consolidation of iovec-related low-level
> routines in qemu.
>
> The plan is to make library functions more understandable,
> consistent and useful, and to drop numerous implementations
> of the same thing.
>
> The patch changes prototypes of several iov and qiov functions
> to match each other, changes types of arguments for some
> functions, _swaps_ some function arguments with each other,
> and makes use of common code in r/w path.
>
> The result of all these changes.
>
> 1. Most qiov-related (qemu_iovec_*) functions now accepts
> 'offset' parameter to specify from which (byte) position to
> start operation. This is added for _memset (removing
> _memset_skip), _from_buffer (allowing to copy a bounce-
> buffer to a middle of qiov). Typical:
>
> size_t qemu_iovec_memset(QEMUIOVector *qiov, size_t offset,
> int c, size_t bytes);
>
> 2. All functions that accepts this `offset' argument does
> it in a similar manner, following the
> iov, fromwhere, what, bytes
> pattern. This is consistent with (updated) iov_send()
> and iov_recv() and friends, where `offset' and `bytes'
> arguments were _renamed_, with the following prototypes:
>
> ssize_t iov_send(sockfd, iov, iov_cnt size_t offset, size_t bytes)
>
> instead of
>
> int qemu_sendv(sockfd, iov, int len, int iov_offset)
>
> See how offset & bytes are used in the same way as for iov_*
> and qemu_iovec_*. A few callers of these are verified and
> converted.
>
> 3. Always use iov_cnt (number of iov entries) together with
> iov, to be able to verify that we don't go past the array.
> iov_send (former qemu_sendv) and iov_recv accepts one extra
> argument now, as are all other derivates (qemu_co_sendv etc).
>
> 4. Used size_t instead of various variations for byte counts.
> Including qemu_iovec_copy which used uint64_t(!) type.
>
> 5. Function arguments are renamed to better match with their
> actual meaning. Compare new and original prototype of
> qemu_sendv() above: old prototype with `len' does not
> tell if `len' refers to number of iov elements (as
> regular writev() call) or to number of data bytes.
> Ditto for several usages of `count' for some qemu_iovec_*,
> which is also replaced to `bytes'.
>
> 5. One implementation of the code remain. For example,
> qemu_iovec_from_buffer() uses iov_from_buf() directly,
> instead of repeating the same code.
>
> The resulting function usage is much more consistent, the
> functions themselves are nice and understandable, which
> means they're easier to use and less error-prone.
>
> This patchset also consolidates a few low-level send&recv
> functions into one, since both versions were the same
> (and were finally calling common function anyway).
> This is done by exporting a common send_recv function
> with one extra bool argument, and making current send&recv
> to be just #defines.
>
> And while at it all, also made some implementations shorter,
> cleaner and much easier to read/understand, and add some
> code comments.
>
> The read&write consolidation has great potential for the
> block layer, as has been demonstrated before.
> Unification and generalization of qemu_iovec_* functions
> will let to optimize/simplify some more code in block/*,
> especially qemu_iovec_memset() and _from_buffer() (this
> optimization/simplification is already used in qcow2.c
> a bit).
>
> The resulting thing should behave like current/existing
> code, there should be no behavor changes, just some
> shuffling and a bit of sanity checks. It has been tested
> slightly, by booting different guests out of different
> image formats and doing some i/o, after each of the 11
> patches, and it all works correctly so far.
>
> Changes since v3:
>
> - rename qemu_sendv(), qemu_sendv_recvv() to iov_send(),
> iov_send_recv() and move them from qemu-common.h and
> cutils.c to iov.h and iov.c.
> - add new argument, iov_cnt, to all send/recv-related
> functions (iov_send_recv(), qemu_co_sendv_recv() etc).
> This resulted in a bit more changes in other places,
> some of which, while simple, may still be non-obvious
> (block/nbd.c and block/sheepdog.c).
> Due to the rename above and to introduction of the
> new iov_cnt arg, the function signatures are changed
> so no old code using new function wrongly is possible.
> - patch that changes iov_from_buf() & iov_to_buf() is
> split into two halves: prototype changes and rewrite.
> - rewrite iov_send_recv() (former qemu_sendv_recvv())
> again, slightly, to use newly introduced iov_cnt arg.
>
> Changes since v2:
>
> - covered iov.[ch] with iov_*() functions which contained
> similar functionality
> - changed tabs to spaces as per suggestion by Kevin
> - explicitly allow to use large sizes for frombuf/tobuf
> functions and friends, stopping at the end of iovec
> in case more bytes requested when available, and
> _returning_ number of actual bytes processed, but
> made it extra clear what a return value will be.
> - used ssize_t for sendv/recvv instead of int, to
> be consistent with all system headers and other
> places in qemu
> - fix/clarify a case in my qemu_co_sendv_recvv()
> of handling zero reads(recvs) and writes(sends).
> - covered qemu_iovec_to_buf() to have the same
> pattern as other too (was missing in v2), and
> use it in qcow2.c right away to simplify things
> - spotted and removed wrong usage of qiov instead of
> plain iov in posix-aio-compat.c
>
> What is _not_ covered:
>
> - suggestion by pbonzini to not use macros for
> access methods to call sendv_recvv with an
> extra true/false argument: I still think the
> usage of macros here is better than anything
> else.
> - maybe re-shuffling of all this stuff into
> different headers -- we already have iov.h,
> maybe rename it to qemu-iov.h for consistency
> and move all iov-related functions into there
> (and ditto for cutils.c => (qemu-)iov.c).
>
> Michael Tokarev (11):
> virtio-serial-bus: use correct lengths in control_out() message
> change iov_* function prototypes to be more appropriate
> rewrite iov_* functions
> consolidate qemu_iovec_memset{,_skip}() into single function and use
> existing iov_memset()
> allow qemu_iovec_from_buffer() to specify offset from which to start copying
> consolidate qemu_iovec_copy() and qemu_iovec_concat() and make them
> consistent
> change qemu_iovec_to_buf() to match other to,from_buf functions
> rename qemu_sendv to iov_send, change proto and move declarations to iov.h
> export iov_send_recv() and use it in iov_send() and iov_recv()
> cleanup qemu_co_sendv(), qemu_co_recvv() and friends
> rewrite iov_send_recv() and move it to iov.c
>
> block.c | 12 ++--
> block/curl.c | 6 +-
> block/iscsi.c | 2 +-
> block/nbd.c | 16 ++--
> block/qcow.c | 4 +-
> block/qcow2.c | 19 ++---
> block/qed.c | 10 +-
> block/rbd.c | 2 +-
> block/sheepdog.c | 6 +-
> block/vdi.c | 4 +-
> cutils.c | 234 ++++++-----------------------------------------
> hw/9pfs/virtio-9p.c | 8 +-
> hw/rtl8139.c | 2 +-
> hw/usb/core.c | 6 +-
> hw/virtio-balloon.c | 4 +-
> hw/virtio-net.c | 4 +-
> hw/virtio-serial-bus.c | 10 +-
> iov.c | 194 +++++++++++++++++++++++++++++-----------
> iov.h | 77 +++++++++++++++--
> linux-aio.c | 4 +-
> net.c | 2 +-
> posix-aio-compat.c | 8 +-
> qemu-common.h | 56 +++++-------
> qemu-coroutine-io.c | 83 ++++++------------
> 24 files changed, 357 insertions(+), 416 deletions(-)
>
Looks good.
Paolo
