From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49781) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZxN2t-0007Xu-5j for qemu-devel@nongnu.org; Fri, 13 Nov 2015 17:42:16 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZxN2r-0003M4-M5 for qemu-devel@nongnu.org; Fri, 13 Nov 2015 17:42:14 -0500 From: John Snow References: <1447345846-15624-1-git-send-email-pl@kamp.de> <1447345846-15624-2-git-send-email-pl@kamp.de> Message-ID: <5646673C.3080104@redhat.com> Date: Fri, 13 Nov 2015 17:42:04 -0500 MIME-Version: 1.0 In-Reply-To: <1447345846-15624-2-git-send-email-pl@kamp.de> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH V4 1/6] ide/atapi: make PIO read requests async List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Lieven , qemu-devel@nongnu.org, qemu-block@nongnu.org Cc: kwolf@redhat.com, stefanha@gmail.com, jcody@redhat.com, famz@redhat.com On 11/12/2015 11:30 AM, Peter Lieven wrote: > PIO read requests on the ATAPI interface used to be sync blk requests. > This has two significant drawbacks. First the main loop hangs util an > I/O request is completed and secondly if the I/O request does not > complete (e.g. due to an unresponsive storage) Qemu hangs completely. > > Note: Due to possible race conditions requests during an ongoing > elementary transfer are still sync. > > Signed-off-by: Peter Lieven > --- > hw/ide/atapi.c | 97 ++++++++++++++++++++++++++++++++++++++++++++++++++-------- > 1 file changed, 85 insertions(+), 12 deletions(-) > > diff --git a/hw/ide/atapi.c b/hw/ide/atapi.c > index 747f466..cfd2d63 100644 > --- a/hw/ide/atapi.c > +++ b/hw/ide/atapi.c > @@ -105,33 +105,98 @@ static void cd_data_to_raw(uint8_t *buf, int lba) > memset(buf, 0, 288); > } > > -static int cd_read_sector(IDEState *s, int lba, uint8_t *buf, int sector_size) > +static int > +cd_read_sector_sync(IDEState *s) > { > int ret; > > - switch(sector_size) { > +#ifdef DEBUG_IDE_ATAPI > + printf("cd_read_sector_sync: lba=%d\n", s->lba); > +#endif > + > + switch (s->cd_sector_size) { > case 2048: > block_acct_start(blk_get_stats(s->blk), &s->acct, > 4 * BDRV_SECTOR_SIZE, BLOCK_ACCT_READ); > - ret = blk_read(s->blk, (int64_t)lba << 2, buf, 4); > + ret = blk_read(s->blk, (int64_t)s->lba << 2, > + s->io_buffer, 4); > block_acct_done(blk_get_stats(s->blk), &s->acct); > break; > case 2352: > block_acct_start(blk_get_stats(s->blk), &s->acct, > 4 * BDRV_SECTOR_SIZE, BLOCK_ACCT_READ); > - ret = blk_read(s->blk, (int64_t)lba << 2, buf + 16, 4); > + ret = blk_read(s->blk, (int64_t)s->lba << 2, > + s->io_buffer + 16, 4); > block_acct_done(blk_get_stats(s->blk), &s->acct); > if (ret < 0) > return ret; > - cd_data_to_raw(buf, lba); > + cd_data_to_raw(s->io_buffer, s->lba); > break; > default: > ret = -EIO; > break; > } > + > + if (!ret) { > + s->lba++; > + s->io_buffer_index = 0; > + } > + > return ret; > } > > +static void cd_read_sector_cb(void *opaque, int ret) > +{ > + IDEState *s = opaque; > + > + block_acct_done(blk_get_stats(s->blk), &s->acct); > + > +#ifdef DEBUG_IDE_ATAPI > + printf("cd_read_sector_cb: lba=%d ret=%d\n", s->lba, ret); > +#endif > + > + if (ret < 0) { > + ide_atapi_io_error(s, ret); > + return; > + } > + > + if (s->cd_sector_size == 2352) { > + cd_data_to_raw(s->io_buffer, s->lba); > + } > + > + s->lba++; > + s->io_buffer_index = 0; > + s->status &= ~BUSY_STAT; > + > + ide_atapi_cmd_reply_end(s); > +} > + > +static int cd_read_sector(IDEState *s) > +{ > + if (s->cd_sector_size != 2048 && s->cd_sector_size != 2352) { > + return -EINVAL; > + } > + > + s->iov.iov_base = (s->cd_sector_size == 2352) ? > + s->io_buffer + 16 : s->io_buffer; > + > + s->iov.iov_len = 4 * BDRV_SECTOR_SIZE; > + qemu_iovec_init_external(&s->qiov, &s->iov, 1); > + > +#ifdef DEBUG_IDE_ATAPI > + printf("cd_read_sector: lba=%d\n", s->lba); > +#endif > + > + block_acct_start(blk_get_stats(s->blk), &s->acct, > + 4 * BDRV_SECTOR_SIZE, BLOCK_ACCT_READ); > + > + blk_aio_readv(s->blk, (int64_t)s->lba << 2, &s->qiov, 4, > + cd_read_sector_cb, s); > + > + s->status |= BUSY_STAT; > + return 0; > +} > + > void ide_atapi_cmd_ok(IDEState *s) > { > s->error = 0; > @@ -182,18 +247,27 @@ void ide_atapi_cmd_reply_end(IDEState *s) > ide_atapi_cmd_ok(s); > ide_set_irq(s->bus); > #ifdef DEBUG_IDE_ATAPI > - printf("status=0x%x\n", s->status); > + printf("end of transfer, status=0x%x\n", s->status); > #endif > } else { > /* see if a new sector must be read */ > if (s->lba != -1 && s->io_buffer_index >= s->cd_sector_size) { > - ret = cd_read_sector(s, s->lba, s->io_buffer, s->cd_sector_size); > - if (ret < 0) { > - ide_atapi_io_error(s, ret); > + if (!s->elementary_transfer_size) { > + ret = cd_read_sector(s); > + if (ret < 0) { > + ide_atapi_io_error(s, ret); > + } > return; > + } else { > + /* rebuffering within an elementary transfer is > + * only possible with a sync request because we > + * end up with a race condition otherwise */ > + ret = cd_read_sector_sync(s); > + if (ret < 0) { > + ide_atapi_io_error(s, ret); > + return; > + } > } > - s->lba++; > - s->io_buffer_index = 0; > } > if (s->elementary_transfer_size > 0) { > /* there are some data left to transmit in this elementary > @@ -275,7 +349,6 @@ static void ide_atapi_cmd_read_pio(IDEState *s, int lba, int nb_sectors, > s->io_buffer_index = sector_size; > s->cd_sector_size = sector_size; > > - s->status = READY_STAT | SEEK_STAT; > ide_atapi_cmd_reply_end(s); > } > > Had to rebase against Berto's patches, but nothing major. You can see my rebase at: https://github.com/jnsnow/qemu/tree/review-plieven Reviewed-by: John Snow