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Simple Rust driver that touches real hardware: PR 6 - #435

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Rust-for-Linux:rustfrom
TheSven73:rust-for-linux-pr6
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Simple Rust driver that touches real hardware: PR 6#435
TheSven73 wants to merge 2 commits into
Rust-for-Linux:rustfrom
TheSven73:rust-for-linux-pr6

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@TheSven73

@TheSven73TheSven73 commented Jul 8, 2021

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Simple Rust driver that touches real h/w: step 6

@alex and @ojeda suggested that #254 should be split into smaller PRs, so they can be reviewed and merged individually.

Roadmap:

  • platform_device
  • devicetree (of) matching
  • probe
  • DrvData
  • passing DrvData as Borrowed (you are here)
  • DrvData references in PlatformDriver trait
  • regmap/iomem

Sven Van Asbroeck added 2 commits July 8, 2021 12:07
Sven Van Asbroeck
platdev: introduce shutdown callback
15d3bfd
Before proceeding with the trickier aspects of platdev (and the
driver model in general), add a `PlatformDriver` callback which
accesses its `PlatData` as a `Borrowed`.
The majority of `bindings::platform_driver` callbacks access their
platform data by reference. So it would be prudent to have at least
one callback that demonstrates this behaviour.
We pick `shutdown` because it is trivial to implement, and easy to
trigger by executing `shutdown -P now` in the shell.
Signed-off-by: Sven Van Asbroeck <thesven73@gmail.com>
Sven Van Asbroeck
bcm2835_rng: demo shutdown by adding per-device context
a1c8a56
Add per-device context, which simply contains a single zero `u32`.
It gets wrapped inside a `Ref<>` so it can be passed to multiple
`FileOpener`s. Note that it's not protected by a lock, so the
context inside the `Ref` is immutable.
Use the per-device context to demonstrate that:
- it can be accessed from inside the `FileOpener`
(by returning the zero `u32` on `read`)
- it can be accessed as a `Borrowed` value from inside `shutdown`
Signed-off-by: Sven Van Asbroeck <thesven73@gmail.com>
@TheSven73

TheSven73 commented Jul 8, 2021•
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@ojeda@wedsonaf I noticed that there has been a lot of ongoing LKML (or ksummit?) discussion re. "real driver", "devm", "kernel and rust lifetimes", etc. With that in mind, I'd appreciate if you could let me know whether the goal of these PRs is still worth pursuing, needs adjustment, or has been superseded by advice or events. Just so we can all use our valuable time wisely.

@ojeda

ojeda commented Jul 8, 2021

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@TheSven73 Definitely. The discussion is still going (I just sent a message there), so let's see what they say about letting us come up with our own APIs to manage objects on the Rust side. Because if we can do that, more options get unlocked for us.

@TheSven73

TheSven73 commented Jul 8, 2021

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"parked" until we have more LKML feedback, and updated strategy.

ojeda pushed a commit that referenced this pull request Dec 20, 2021
Dust Li@davem330
net/smc: fix wrong list_del in smc_lgr_cleanup_early
789b6cc
smc_lgr_cleanup_early() meant to delete the link
group from the link group list, but it deleted
the list head by mistake.
This may cause memory corruption since we didn't
remove the real link group from the list and later
memseted the link group structure.
We got a list corruption panic when testing:
[ 231.277259] list_del corruption. prev->next should be ffff8881398a8000, but was 0000000000000000
[ 231.278222] ------------[ cut here ]------------
[ 231.278726] kernel BUG at lib/list_debug.c:53!
[ 231.279326] invalid opcode: 0000 [#1] SMP NOPTI
[ 231.279803] CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 5.10.46+ #435
[ 231.280466] Hardware name: Alibaba Cloud ECS, BIOS 8c24b4c 04/01/2014
[ 231.281248] Workqueue: events smc_link_down_work
[ 231.281732] RIP: 0010:__list_del_entry_valid+0x70/0x90
[ 231.282258] Code: 4c 60 82 e8 7d cc 6a 00 0f 0b 48 89 fe 48 c7 c7 88 4c
60 82 e8 6c cc 6a 00 0f 0b 48 89 fe 48 c7 c7 c0 4c 60 82 e8 5b cc 6a 00 <0f>
0b 48 89 fe 48 c7 c7 00 4d 60 82 e8 4a cc 6a 00 0f 0b cc cc cc
[ 231.284146] RSP: 0018:ffffc90000033d58 EFLAGS: 0001029
[ 231.284685] RAX: 0000000000000054 RBX: ffff8881398a8000 RCX: 0000000000000000
[ 231.285415] RDX: 0000000000000001 RSI: ffff88813bc18040 RDI: ffff88813bc18040
[ 231.286141] RBP: ffffffff8305ad40 R08: 0000000000000003 R09: 0000000000000001
[ 231.286873] R10: ffffffff82803da0 R11: ffffc90000033b90 R12: 0000000000000001
[ 231.287606] R13: 0000000000000000 R14: ffff8881398a8000 R15: 0000000000000003
[ 231.288337] FS: 0000000000000000(0000) GS:ffff88813bc00000(0000) knlGS:0000000000000000
[ 231.289160] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 231.289754] CR2: 0000000000e72058 CR3: 000000010fa96006 CR4: 00000000003706f0
[ 231.290485] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 231.291211] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 231.291940] Call Trace:
[ 231.292211] smc_lgr_terminate_sched+0x53/0xa0
[ 231.292677] smc_switch_conns+0x75/0x6b0
[ 231.293085] ? update_load_avg+0x1a6/0x590
[ 231.293517] ? ttwu_do_wakeup+0x17/0x150
[ 231.293907] ? update_load_avg+0x1a6/0x590
[ 231.294317] ? newidle_balance+0xca/0x3d0
[ 231.294716] smcr_link_down+0x50/0x1a0
[ 231.295090] ? __wake_up_common_lock+0x77/0x90
[ 231.295534] smc_link_down_work+0x46/0x60
[ 231.295933] process_one_work+0x18b/0x350
Fixes: a0a62ee ("net/smc: separate locks for SMCD and SMCR link group lists")
Signed-off-by: Dust Li <dust.li@linux.alibaba.com>
Acked-by: Karsten Graul <kgraul@linux.ibm.com>
Reviewed-by: Tony Lu <tonylu@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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@TheSven73@ojeda