Re: SYSFS "errors"

Hi, On Mon, Feb 18, 2013 at 09:49:16AM -0800, Greg KH wrote:

quoted

Input/output error - /sys/devices/cpu/power/autosuspend_delay_ms

The issue with this file is, if the power.use_autosuspend flag is not
set for the device, then it can't be read or written to.  This flag
changes dynamically with the system state
(__pm_runtime_use_autosuspend() can change it), so we can't just not
show the file if the flag is not set properly, sorry.

So the "error" is correct here, as is the 0644 file value.

hmm... we could create the file at pm_runtime_enable() time and remove
it on pm_runtime_disable() time, no ? Addin Rafael to Cc

quoted

No such device or address - /sys/devices/pci0000:00/0000:00:1d.7/usb2/2-5/2-5.1/2-5.1.1/2-5.1.1:1.0/host100/target100:0:0/100:0:0:0/block/sdc/trace/pid
No such device or address - /sys/devices/pci0000:00/0000:00:1d.7/usb2/2-5/2-5.1/2-5.1.1/2-5.1.1:1.0/host100/target100:0:0/100:0:0:0/block/sdc/trace/end_lba
No such device or address - /sys/devices/pci0000:00/0000:00:1d.7/usb2/2-5/2-5.1/2-5.1.1/2-5.1.1:1.0/host100/target100:0:0/100:0:0:0/block/sdc/trace/enable
No such device or address - /sys/devices/pci0000:00/0000:00:1d.7/usb2/2-5/2-5.1/2-5.1.1/2-5.1.1:1.0/host100/target100:0:0/100:0:0:0/block/sdc/trace/act_mask
No such device or address - /sys/devices/pci0000:00/0000:00:1d.7/usb2/2-5/2-5.1/2-5.1.1/2-5.1.1:1.0/host100/target100:0:0/100:0:0:0/block/sdc/trace/start_lba
Invalid argument - /sys/devices/pci0000:00/0000:00:1f.2/ata2/host1/scsi_host/host1/em_buffer
Invalid argument - /sys/devices/pci0000:00/0000:00:1f.2/ata2/host1/target1:0:0/1:0:0:0/sw_activity
Operation not supported - /sys/devices/pci0000:00/0000:00:1f.2/ata2/host1/target1:0:0/1:0:0:0/unload_heads

SCSI fun, go poke the SCSI developers about these files, I know nothing
about them, nor do I really want to :)

quoted

No such device - /sys/devices/system/edac/mc/mc0/sdram_scrub_rate

Odd, go ask the edac developers

will do ;-)

quoted

Input/output error - /sys/devices/system/memory/soft_offline_page
Input/output error - /sys/devices/system/memory/hard_offline_page

These both should be mode 0400, not 0644, they have no 'show' attribute,
that's a bug, care to make up a patch that I can take?  Or I can, let me
know.

sure, will send in a bit.

quoted

Invalid argument - /sys/devices/virtual/net/lo/speed
Invalid argument - /sys/devices/virtual/net/lo/duplex

Ask the network developers, odds are, the loopback device doesn't really
have a speed :)

right ;-)

quoted

No such device or address - /sys/devices/virtual/block/loop0/trace/pid
No such device or address - /sys/devices/virtual/block/loop0/trace/end_lba
No such device or address - /sys/devices/virtual/block/loop0/trace/enable
No such device or address - /sys/devices/virtual/block/loop0/trace/act_mask
No such device or address - /sys/devices/virtual/block/loop0/trace/start_lba

Hm, these show up for virtual block devices as well, maybe they aren't
scsi specific, but rather block specific, go poke the block developers
then.

yeah, I was looking into these a while ago. They're created by
blk_trace_init_sysfs() which is called by blk_register_queue() but I
wonder if we couldn't defer the creation of those so that:

sysfs_blk_trace_attr_show():

1639         bdev = bdget(part_devt(p));
1640         if (bdev == NULL)
1641                 goto out;
1642 
1643         q = blk_trace_get_queue(bdev);
1644         if (q == NULL)
1645                 goto out_bdput;

never fail (meaning they could be removed), adding some block folks to
the loop.

-- 
balbi