[PATCH 00/14] Cleanup chardev instances with helper function
by Logan Gunthorpe
Hello,
Our story for this patch-set begins with a new driver I wrote and am in
the process of submitting upstream. That driver creates a fairly
standard char device and the code for it was copied from a similar
instance in device-dax. However, upon review, Greg Kroah-Hartman
noticed [1] a suspicious line that assigned to the parent field of
the underlying kobject for the char device.
I removed that from my code and endeavoured to remove it from the
code I copied as well. However, Dan Williams pointed out [2] that this
code is necessary for correct reference counting of the underlying
structures. This prompted me to do a fair bit more research and
investigation into whats going on and I found it to be a common pattern.
(Although misleading and though required to be correct, frequently
forgotten.) This pattern is used in at least 15 places in the kernel
and probably should have been used in at least 5 more.
This patch-set aims to correct this and hopefully prevent future
developers from wasting their time on it. The first patch introduces
a new helper API as originally proposed by Dan Williams [3]. Please
see the commit message for that patch for a longer description of the
problem and history.
The subsequent patches either update correct instances to use the
new API or fix incorrect usages to ensure the cdev correctly takes
a reference count using the new API (this is noted in those patches).
This moves all except four of the cdev.kobj.parent usages into the one
cdev function, the remaining four are in the infiniband subsystem and
I've left alone because that subsystem seems to make use of kobjects
directly (instead of struct devices). These are noted in patch 7 of
this series.
This series is based on v4.10 with the exception of the last patch
which is for my new driver which, as yet, has not been accepted
upstream.
@Dan the first patch in this series will need your sign-off.
Thanks,
Logan
[1] https://lkml.org/lkml/2017/2/10/370
[2] https://lkml.org/lkml/2017/2/10/607
[3] https://lkml.org/lkml/2017/2/13/700
Logan Gunthorpe (14):
chardev: add helper function to register char devs with a struct
device
device-dax: utilize new device_add_cdev helper function
input: utilize new device_add_cdev helper function
gpiolib: utilize new device_add_cdev helper function
tpm-chip: utilize new device_add_cdev helper function
platform/chrome: utilize new device_add_cdev helper function
infiniband: utilize new device_add_cdev helper function
iio:core: utilize new device_add_cdev helper function
media: utilize new device_add_cdev helper function
mtd: utilize new device_add_cdev helper function
rapidio: utilize new device_add_cdev helper function
rtc: utilize new device_add_cdev helper function
scsi: utilize new device_add_cdev helper function
switchtec: utilize new device_add_cdev helper function
drivers/char/tpm/tpm-chip.c | 3 +--
drivers/dax/dax.c | 5 ++---
drivers/gpio/gpiolib.c | 3 +--
drivers/iio/industrialio-core.c | 3 +--
drivers/infiniband/core/ucm.c | 8 +++++---
drivers/input/evdev.c | 3 +--
drivers/input/joydev.c | 3 +--
drivers/input/mousedev.c | 3 +--
drivers/media/cec/cec-core.c | 3 +--
drivers/media/media-devnode.c | 3 +--
drivers/mtd/ubi/build.c | 8 +++++---
drivers/mtd/ubi/vmt.c | 10 +++++-----
drivers/pci/switch/switchtec.c | 3 +--
drivers/platform/chrome/cros_ec_dev.c | 6 ++----
drivers/rapidio/devices/rio_mport_cdev.c | 9 ++++++---
drivers/rtc/rtc-dev.c | 3 +--
drivers/scsi/osd/osd_uld.c | 9 +++++----
fs/char_dev.c | 24 ++++++++++++++++++++++++
include/linux/cdev.h | 1 +
19 files changed, 65 insertions(+), 45 deletions(-)
--
2.1.4
3 years, 10 months
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by 胡院
呈：linux-nvdimm
附*件*内*容 请*查*收
2017-2-23 5:18:54
3 years, 10 months
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3 years, 10 months
Re:秘/书/助/理/职能如何提升
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呈：linux-nvdimm
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2017-2-22
22:11:16
3 years, 10 months
如何提高公司整体业绩
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Received: from WS-web (ksqoas(a)vwg.org)
Date: 星期六 2017-2-22 21:25:46+0800
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详细 内容 烦请 查阅 附件
3 years, 10 months
[PATCH 0/6] second round of tracepoints for DAX
by Ross Zwisler
This second round of DAX tracepoint patches adds tracing to the PTE fault
path (dax_iomap_pte_fault(), dax_pfn_mkwrite(), dax_load_hole(),
dax_insert_mapping()) and to the writeback path
(dax_writeback_mapping_range(), dax_writeback_one()).
The purpose of this tracing is to give us a high level view of what DAX is
doing, whether faults are being serviced by PMDs or PTEs, and by real
storage or by zero pages covering holes.
I do have some patches nearly ready which also add tracing to
grab_mapping_entry() and dax_insert_mapping_entry(). These are more
targeted at logging how we are interacting with the radix tree, how we use
empty entries for locking, whether we "downgrade" huge zero pages to
4k PTE sized allocations, etc. In the end it seemed to me that this might
be too detailed to have as constantly present tracepoints, but if anyone
sees value in having tracepoints like this in the DAX code permanently
(Jan?), please let me know and I'll add those last two patches.
All these tracepoints were done to be consistent with the style of the XFS
tracepoints and with the existing DAX PMD tracepoints.
This series applies cleanly to the current mmots/master:
commit 35aa45ffe8d9 ("pci: test for unexpectedly disabled bridges")
and I'm hoping that it'll end up going to Linus through akpm's -mm tree.
Thanks,
- Ross
Ross Zwisler (6):
dax: add tracepoints to dax_iomap_pte_fault()
dax: add tracepoints to dax_pfn_mkwrite()
dax: add tracepoints to dax_load_hole()
dax: add tracepoints to dax_writeback_mapping_range()
dax: add tracepoint to dax_writeback_one()
dax: add tracepoint to dax_insert_mapping()
fs/dax.c | 44 ++++++++++----
include/trace/events/fs_dax.h | 130 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 163 insertions(+), 11 deletions(-)
--
2.9.3
3 years, 10 months
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3 years, 11 months
extent-status tree for DAX ?
by Sanketh Nalli
Hi,
I was wondering if we need the extent-status tree
for DAX-like devices ? Says here that it can get consume a lot of memory
and offer poor performance if the on-DAX file is fragmented. Without the status tree, one could simple walk the on-DAX extent tree to get to the file data pages and this is possible with DAX-like devices.
http://lxr.free-electrons.com/source/fs/ext4/extents_status.c#L117
A few simple experiments with filebench's random read workload clearly
bring out the difference in performance with a fragmented and contiguous
file on-DAX. A lot of time is spent in walking the status tree, which can be
avoided, I guess. Please let me know what you think.
--
S. Nalli
Graduate Student, Computer Sciences
University of Wisconsin-Madison, USA
3 years, 11 months
UPS parcel #9335463 delivery problem
by fragforc＠apache.tor.sl.cumulusservers.com
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3 years, 11 months
