On Thu, Oct 19, 2006 at 09:22:59AM -0600, Fajun Chen wrote:
> Note that it took less than 3 seconds for ata1 to be reconfigured as
> sg1. My user space application opened sg1 for ioctl -
> SCSI_IOCTL_GET_BUS_NUMBER once it's available but got block for around
> 11 seconds. It seems the ioctl call was unblocked until the error
> recovery on ata2 was completed at time stamp 14068. I suspect it's
> blocked in the scsi_ioctl.c:
> int scsi_ioctl(struct scsi_device *sdev, int cmd, void __user *arg)
> {
> char scsi_cmd[MAX_COMMAND_SIZE];
>
> /* No idea how this happens.... */
> if (!sdev)
> return -ENXIO;
>
> /*
> * If we are in the middle of error recovery, don't let anyone
> * else try and use this device. Also, if error recovery fails, it
> * may try and take the device offline, in which case all further
> * access to the device is prohibited.
> */
> if (!scsi_block_when_processing_errors(sdev))
> return -ENODEV;
> ...
> }
>
> If the ioctl() on sg1/ata1 was not blocked due to ata2 error recovery,
> then where it could be blocked?
My test says otherwise. What I did was...
1. execute "./testsg /dev/sg0"
2. hotplug one harddrive (took ~3secs)
3. hotplug another drive (took ~6secs)
The result is...
# ./testsg /dev/sg0
ata6: exception Emask 0x10 SAct 0x0 SErr 0x0 action 0x2 frozen
[ 127.205451] ata6: (irq_stat 0x00b40090, PHY RDY changed)
[ 127.721061] ata6: waiting for device to spin up (8 secs)
[ 133.077235] ata5: exception Emask 0x10 SAct 0x0 SErr 0x0 action 0x2 frozen
[ 133.084452] ata5: (irq_stat 0x00a00080, device exchanged)
[ 133.599527] ata5: waiting for device to spin up (8 secs)
[ 135.903791] ata6: soft resetting port
[ 136.007637] ata6: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
[ 136.018667] ata6.00: ATA-7, max UDMA7, 312581808 sectors: LBA48 NCQ (depth 31
/32)
[ 136.026217] ata6.00: ata6: dev 0 multi count 16
[ 136.057713] ata6.00: configured for UDMA/100
[ 136.062050] ata6: EH complete
[ 137.062103] scsi 5:0:0:0: Direct-Access ATA SAMSUNG HD160JJ ZM10 PQ
: 0 ANSI: 5
[ 137.071696] SCSI device sda: 312581808 512-byte hdwr sectors (160042 MB)
[ 137.078695] sda: Write Protect is off
[ 137.082751] SCSI device sda: drive cache: write back
[ 137.088087] SCSI device sda: 312581808 512-byte hdwr sectors (160042 MB)
[ 137.095156] sda: Write Protect is off
[ 137.099203] SCSI device sda: drive cache: write back
[ 137.104261] sda: unknown partition table
[ 137.115839] sd 5:0:0:0: Attached scsi disk sda
[ 137.120480] sd 5:0:0:0: Attached scsi generic sg0 type 0
open succeeded after 13859ms
ioctl completed after 0ms, rc=0, bus=5
--> ioctl is executed back-to-back to open
[root@jtj:~/ttmp]#
--> testsg is complete at this point
[ 141.798233] ata5: soft resetting port
[ 141.902079] ata5: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
[ 141.909519] ata5.00: ATA-7, max UDMA/133, 160086528 sectors: LBA NCQ (depth 3
1/32)
[ 141.917170] ata5.00: ata5: dev 0 multi count 0
[ 141.923737] ata5.00: configured for UDMA/100
[ 141.928073] ata5: EH complete
[ 142.928568] scsi 4:0:0:0: Direct-Access ATA Maxtor 6B080M0 BANC PQ
: 0 ANSI: 5
[ 142.938171] SCSI device sdb: 160086528 512-byte hdwr sectors (81964 MB)
[ 142.945046] sdb: Write Protect is off
[ 142.949056] SCSI device sdb: drive cache: write back
[ 142.954352] SCSI device sdb: 160086528 512-byte hdwr sectors (81964 MB)
[ 142.961186] sdb: Write Protect is off
[ 142.965239] SCSI device sdb: drive cache: write back
[ 142.970289] sdb: unknown partition table
[ 142.992997] sd 4:0:0:0: Attached scsi disk sdb
[ 142.997629] sd 4:0:0:0: Attached scsi generic sg1 type 0
Your wait is somewhere else.
--
tejun
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/time.h>
#include <time.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <scsi/scsi.h>
int main(int argc, char **argv)
{
const struct timespec ts_1ms = { 0, 1000000 };
struct timeval tv0, tv1, result;
unsigned long interval;
int rc, fd, bus;
if (argc < 2)
fprintf(stderr, "Usage: testsg SGFILE\n");
gettimeofday(&tv0, NULL);
while (1) {
fd = open(argv[1], O_RDONLY);
if (fd >= 0 || errno != ENOENT)
break;
nanosleep(&ts_1ms, NULL);
}
gettimeofday(&tv1, NULL);
timersub(&tv1, &tv0, &result);
interval = result.tv_sec * 1000 + result.tv_usec / 1000;
if (fd < 0) {
fprintf(stderr, "open failed (%s) after %lums\n",
strerror(errno), interval);
return 1;
}
printf("open succeeded after %lums\n", interval);
gettimeofday(&tv0, NULL);
rc = ioctl(fd, SCSI_IOCTL_GET_BUS_NUMBER, &bus);
gettimeofday(&tv1, NULL);
timersub(&tv1, &tv0, &result);
interval = result.tv_sec * 1000 + result.tv_usec / 1000;
printf("ioctl completed after %lums, rc=%d, bus=%d\n",
interval, rc, bus);
return 0;
}
