From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54538) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZtVcn-0005ig-7w for qemu-devel@nongnu.org; Tue, 03 Nov 2015 02:03:22 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZtVcj-0006T9-6n for qemu-devel@nongnu.org; Tue, 03 Nov 2015 02:03:21 -0500 Received: from mx-v6.kamp.de ([2a02:248:0:51::16]:49121 helo=mx01.kamp.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZtVci-0006RL-U8 for qemu-devel@nongnu.org; Tue, 03 Nov 2015 02:03:17 -0500 References: <1444652845-20642-1-git-send-email-pl@kamp.de> <1444652845-20642-2-git-send-email-pl@kamp.de> <5638047A.4090804@redhat.com> From: Peter Lieven Message-ID: <56385C2D.4060903@kamp.de> Date: Tue, 3 Nov 2015 08:03:09 +0100 MIME-Version: 1.0 In-Reply-To: <5638047A.4090804@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 1/4] ide/atapi: make PIO read requests async List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: John Snow , qemu-devel@nongnu.org, qemu-block@nongnu.org Cc: kwolf@redhat.com, stefanha@gmail.com, jcody@redhat.com Am 03.11.2015 um 01:48 schrieb John Snow: > > On 10/12/2015 08:27 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. >> >> Signed-off-by: Peter Lieven >> --- >> hw/ide/atapi.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++++++++------ >> 1 file changed, 84 insertions(+), 9 deletions(-) >> >> diff --git a/hw/ide/atapi.c b/hw/ide/atapi.c >> index 747f466..2271ea2 100644 >> --- a/hw/ide/atapi.c >> +++ b/hw/ide/atapi.c >> @@ -105,11 +105,16 @@ 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 lba, uint8_t *buf) >> { >> int ret; >> >> - switch(sector_size) { >> +#ifdef DEBUG_IDE_ATAPI >> + printf("cd_read_sector_sync: lba=%d\n", 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); >> @@ -129,9 +134,71 @@ static int cd_read_sector(IDEState *s, int lba, uint8_t *buf, int sector_size) >> 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, int lba, void *buf) >> +{ >> + if (s->cd_sector_size != 2048 && s->cd_sector_size != 2352) { >> + return -EINVAL; >> + } >> + >> + s->iov.iov_base = buf; >> + if (s->cd_sector_size == 2352) { >> + buf += 16; >> + } >> + >> + 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", lba); >> +#endif >> + >> + if (blk_aio_readv(s->blk, (int64_t)lba << 2, &s->qiov, 4, >> + cd_read_sector_cb, s) == NULL) { >> + return -EIO; >> + } >> + >> + block_acct_start(blk_get_stats(s->blk), &s->acct, >> + 4 * BDRV_SECTOR_SIZE, BLOCK_ACCT_READ); >> + >> + s->status |= BUSY_STAT; >> + return 0; >> +} >> + >> void ide_atapi_cmd_ok(IDEState *s) >> { >> s->error = 0; >> @@ -182,18 +249,27 @@ 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, s->lba, s->io_buffer); >> + 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, s->lba, s->io_buffer); >> + 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 +351,6 @@ 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); >> } >> >> > This patch looks good to me, apart from Stefan's other comments. Will > you be sending a V3? I can try to merge it for this week before the hard > freeze hits. I will look at this today. Peter