capsules/i2c_master_slave_driver: use grant, enforce single process #2547
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bradjc
previously approved these changes
Apr 22, 2021
lschuermann
reviewed
Apr 23, 2021
| } else { | ||
| return Err((slice, ErrorCode::NOMEM)); | ||
| } | ||
| let app = self.app.expect("cant fail"); |
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Isn't app always equivalent to process_id here, given the logic above? Then I suppose we could just use that and get rid of the expect.
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good call, done
Enforce that only a single process may (implicitly) reserve the nonvirtualized userspace driver. Also, store callbacks and appslices in grant regions.
alistair23
approved these changes
Apr 26, 2021
lschuermann
reviewed
Apr 26, 2021
| _ => Err((slice, ErrorCode::NOSUPPORT)), | ||
| let res = self | ||
| .apps | ||
| .enter(app, |app| { |
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Nit: this technically works, though the ProcessId and Grant region are related but different things and I fear that shadowing the app variable might be confusing. Feel free to not change this if not considered an issue.
bradjc
approved these changes
Apr 26, 2021
|
bors r+ |
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Pull Request Overview
This pull request enforces that only a single process may (implicitly) reserve the nonvirtualized userspace driver. Also, the driver now store callbacks and appslices in grant regions.
This is one of the remaining capsules blocking #2462 .
One observation: repeatedly handling the possibility of a grant entrance (within a single function) failing is a pain. But I do not think it is possible for a grant entrance to fail after the first entrance -- the grant is already allocated at that point, and the process is present. So I omitted the error handling in
command()after the first grant entrance.Testing Strategy
This pull request was tested by compiling.
TODO or Help Wanted
N/A
Documentation Updated
Formatting
make prepush.