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https://gitee.com/bianbu-linux/linux-6.6
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bf15bb38ec
The current ice driver's GNSS write implementation buffers writes and
works through them asynchronously in a kthread. That's bad because:
- The GNSS write_raw operation is supposed to be synchronous[1][2].
- There is no upper bound on the number of pending writes.
Userspace can submit writes much faster than the driver can process,
consuming unlimited amounts of kernel memory.
A patch that's currently on review[3] ("[v3,net] ice: Write all GNSS
buffers instead of first one") would add one more problem:
- The possibility of waiting for a very long time to flush the write
work when doing rmmod, softlockups.
To fix these issues, simplify the implementation: Drop the buffering,
the write_work, and make the writes synchronous.
I tested this with gpsd and ubxtool.
[1] https://events19.linuxfoundation.org/wp-content/uploads/2017/12/The-GNSS-Subsystem-Johan-Hovold-Hovold-Consulting-AB.pdf
"User interface" slide.
[2] A comment in drivers/gnss/core.c:gnss_write():
/* Ignoring O_NONBLOCK, write_raw() is synchronous. */
[3] https://patchwork.ozlabs.org/project/intel-wired-lan/patch/20230217120541.16745-1-karol.kolacinski@intel.com/
Fixes:
|
||
|---|---|---|
| .. | ||
| e1000 | ||
| e1000e | ||
| fm10k | ||
| i40e | ||
| iavf | ||
| ice | ||
| igb | ||
| igbvf | ||
| igc | ||
| ixgbe | ||
| ixgbevf | ||
| e100.c | ||
| Kconfig | ||
| Makefile | ||