From: Douglas Gilbert <dgilbert@interlog.com>
To: Hannes Reinecke <hare@suse.de>, linux-scsi@vger.kernel.org
Cc: martin.petersen@oracle.com, jejb@linux.vnet.ibm.com,
kashyap.desai@broadcom.com
Subject: Re: [PATCH v13 28/45] sg: rework debug info
Date: Thu, 14 Jan 2021 15:21:05 -0500 [thread overview]
Message-ID: <790d2d71-4777-a66a-cdd6-edd1369c7113@interlog.com> (raw)
In-Reply-To: <d9337b54-6d27-b109-9667-5a913f82797f@suse.de>
On 2021-01-14 2:12 a.m., Hannes Reinecke wrote:
> On 1/13/21 11:45 PM, Douglas Gilbert wrote:
>> Since the version 2 driver, the state of the driver can be found
>> with 'cat /proc/scsi/sg/debug'. As the driver becomes more
>> threaded and IO faster (e.g. scsi_debug with a command timer
>> of 5 microseconds), the existing state dump can become
>> misleading as the state can change during the "snapshot". The
>> new approach in this patch is to allocate a buffer of
>> SG_PROC_DEBUG_SZ bytes and use scnprintf() to populate it. Only
>> when the whole state is captured (or the buffer fills) is the
>> output to the caller's terminal performed. The previous
>> approach was line based: assemble a line of information and
>> then output it.
>>
> Hmm. The whole '/proc' business is considered deprecated, and new
> (or updated) drivers should be moving to debugfs.
> Wouldn't it be better to do that, and deprecate /proc/sg, seeing that
> you are rewriting the entire driver anyway?
Well '/proc/scsi/sg/*' is in the public interface, so to remove it
represents a breakage. Like many developers I run lots of virtual
terminals with as few as possible logged in as 'root'. So I consider
it a definite advantage that cat /proc/scsi/sg/debug does not need
elevated permissions like the debugfs equivalent does. The security
folks would probably take the opposite view.
It is in debugfs: cat /sys/kernel/debug/scsi_generic/snapshot
is equivalent to cat /proc/scsi/sg/debug.
So currently we have both. Well not quite as this first series
hasn't been accepted after more than a year of attempts. IMO it
is a bit early to deprecate before the replacement is even in place.
New features are only being placed in debugfs. For example, there
is a new feature in patch 59 of series 2 using the new
ioctl(SG_SET_GET_EXTENDED) and the SG_CTL_FLAGM_SNAP_DEV flag to
programmatically send a snapshot of the sg object tree to
/sys/kernel/debug/scsi_generic/snapped .
Doug Gilbert
next prev parent reply other threads:[~2021-01-14 20:21 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-13 22:44 [PATCH v13 00/45] sg: add v4 interface Douglas Gilbert
2021-01-13 22:44 ` [PATCH v13 01/45] sg: move functions around Douglas Gilbert
2021-01-13 22:44 ` [PATCH v13 02/45] sg: remove typedefs, type+formatting cleanup Douglas Gilbert
2021-01-13 22:44 ` [PATCH v13 03/45] sg: sg_log and is_enabled Douglas Gilbert
2021-01-13 22:44 ` [PATCH v13 04/45] sg: rework sg_poll(), minor changes Douglas Gilbert
2021-01-13 22:44 ` [PATCH v13 05/45] sg: bitops in sg_device Douglas Gilbert
2021-01-13 22:44 ` [PATCH v13 06/45] sg: make open count an atomic Douglas Gilbert
2021-01-13 22:44 ` [PATCH v13 07/45] sg: move header to uapi section Douglas Gilbert
2021-01-13 22:44 ` [PATCH v13 08/45] sg: speed sg_poll and sg_get_num_waiting Douglas Gilbert
2021-01-13 22:44 ` [PATCH v13 09/45] sg: sg_allow_if_err_recovery and renames Douglas Gilbert
2021-01-13 22:44 ` [PATCH v13 10/45] sg: improve naming Douglas Gilbert
2021-01-13 22:44 ` [PATCH v13 11/45] sg: change rwlock to spinlock Douglas Gilbert
2021-01-13 22:44 ` [PATCH v13 12/45] sg: ioctl handling Douglas Gilbert
2021-01-13 22:44 ` [PATCH v13 13/45] sg: split sg_read Douglas Gilbert
2021-01-13 22:44 ` [PATCH v13 14/45] sg: sg_common_write add structure for arguments Douglas Gilbert
2021-01-13 22:44 ` [PATCH v13 15/45] sg: rework sg_vma_fault Douglas Gilbert
2021-01-13 22:44 ` [PATCH v13 16/45] sg: rework sg_mmap Douglas Gilbert
2021-01-13 22:44 ` [PATCH v13 17/45] sg: replace sg_allow_access Douglas Gilbert
2021-01-13 22:44 ` [PATCH v13 18/45] sg: rework scatter gather handling Douglas Gilbert
2021-01-13 22:45 ` [PATCH v13 19/45] sg: introduce request state machine Douglas Gilbert
2021-01-13 22:45 ` [PATCH v13 20/45] sg: sg_find_srp_by_id Douglas Gilbert
2021-01-13 22:45 ` [PATCH v13 21/45] sg: sg_fill_request_element Douglas Gilbert
2021-01-13 22:45 ` [PATCH v13 22/45] sg: printk change %p to %pK Douglas Gilbert
2021-01-13 22:45 ` [PATCH v13 23/45] sg: xarray for fds in device Douglas Gilbert
2021-01-13 22:45 ` [PATCH v13 24/45] sg: xarray for reqs in fd Douglas Gilbert
2021-01-13 22:45 ` [PATCH v13 25/45] sg: replace rq array with xarray Douglas Gilbert
2021-01-13 22:45 ` [PATCH v13 26/45] sg: sense buffer rework Douglas Gilbert
2021-01-13 22:45 ` [PATCH v13 27/45] sg: add sg v4 interface support Douglas Gilbert
2021-01-13 22:45 ` [PATCH v13 28/45] sg: rework debug info Douglas Gilbert
2021-01-14 7:12 ` Hannes Reinecke
2021-01-14 20:21 ` Douglas Gilbert [this message]
2021-01-13 22:45 ` [PATCH v13 29/45] sg: add 8 byte SCSI LUN to sg_scsi_id Douglas Gilbert
2021-01-13 22:45 ` [PATCH v13 30/45] sg: expand sg_comm_wr_t Douglas Gilbert
2021-01-13 22:45 ` [PATCH v13 31/45] sg: add sg_iosubmit_v3 and sg_ioreceive_v3 ioctls Douglas Gilbert
2021-01-13 22:45 ` [PATCH v13 32/45] sg: add some __must_hold macros Douglas Gilbert
2021-01-13 22:45 ` [PATCH v13 33/45] sg: move procfs objects to avoid forward decls Douglas Gilbert
2021-01-13 22:45 ` [PATCH v13 34/45] sg: protect multiple receivers Douglas Gilbert
2021-01-13 22:45 ` [PATCH v13 35/45] sg: first debugfs support Douglas Gilbert
2021-01-13 22:45 ` [PATCH v13 36/45] sg: rework mmap support Douglas Gilbert
2021-01-13 22:45 ` [PATCH v13 37/45] sg: defang allow_dio Douglas Gilbert
2021-01-14 7:15 ` Hannes Reinecke
2021-01-13 22:45 ` [PATCH v13 38/45] sg: warn v3 write system call users Douglas Gilbert
2021-01-13 22:45 ` [PATCH v13 39/45] sg: add mmap_sz tracking Douglas Gilbert
2021-01-14 7:18 ` Hannes Reinecke
2021-01-14 21:40 ` Douglas Gilbert
2021-01-13 22:45 ` [PATCH v13 40/45] sg: remove rcv_done request state Douglas Gilbert
2021-01-14 7:20 ` Hannes Reinecke
2021-01-13 22:45 ` [PATCH v13 41/45] sg: track lowest inactive and await indexes Douglas Gilbert
2021-01-14 7:25 ` Hannes Reinecke
2021-01-13 22:45 ` [PATCH v13 42/45] sg: remove unit attention check for device changed Douglas Gilbert
2021-01-14 7:26 ` Hannes Reinecke
2021-01-13 22:45 ` [PATCH v13 43/45] sg: no_dxfer: move to/from kernel buffers Douglas Gilbert
2021-01-14 7:30 ` Hannes Reinecke
2021-01-14 17:11 ` Douglas Gilbert
2021-01-15 16:17 ` Hannes Reinecke
2021-01-13 22:45 ` [PATCH v13 44/45] sg: [RFC] add blk_poll support Douglas Gilbert
2021-01-14 2:58 ` Douglas Gilbert
2021-01-14 7:35 ` Hannes Reinecke
2021-01-14 16:05 ` Douglas Gilbert
2021-01-15 16:25 ` Hannes Reinecke
2021-01-13 22:45 ` [PATCH v13 45/45] sg: bump version to 4.0.12 Douglas Gilbert
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