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platform_drv: guard against Out_of_* exceptions

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In the scope of alloc_dma_buffer(), Out_of_* exceptions might be thrown
at different stages. By adding a Guard object, we make sure to rollback
already created objects accordingly.

genodelabs/genode#5002
This commit is contained in:
Johannes Schlatow 2023-10-30 15:24:27 +01:00
parent 350a3d9ae4
commit d018cb62f3
1 changed files with 35 additions and 13 deletions
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48
repos/os/src/drivers/platform/session_component.cc
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@ -332,7 +332,32 @@ void Session_component::release_device(Capability<Platform::Device_interface> de
Genode::Ram_dataspace_capability
Session_component::alloc_dma_buffer(size_t const size, Cache cache)
{
Ram_dataspace_capability ram_cap { };
struct Guard {
Constrained_ram_allocator & _env_ram;
Heap & _heap;
bool _cleanup { true };
Ram_dataspace_capability ram_cap { };
struct {
Dma_buffer * buf { nullptr };
};
void disarm() { _cleanup = false; }
Guard(Constrained_ram_allocator & env_ram, Heap & heap)
: _env_ram(env_ram), _heap(heap)
{ }
~Guard()
{
if (_cleanup && buf)
destroy(_heap, buf);
if (_cleanup && ram_cap.valid())
_env_ram.free(ram_cap);
}
} guard { _env_ram, heap() };
/*
* Check available quota beforehand and reflect the state back
@ -348,28 +373,25 @@ Session_component::alloc_dma_buffer(size_t const size, Cache cache)
throw Out_of_ram();
try {
ram_cap = _env_ram.alloc(size, cache);
guard.ram_cap = _env_ram.alloc(size, cache);
} catch (Ram_allocator::Denied) { }
if (!ram_cap.valid()) return ram_cap;
if (!guard.ram_cap.valid()) return guard.ram_cap;
try {
Dma_buffer & buf = _dma_allocator.alloc_buffer(ram_cap,
_env.pd().dma_addr(ram_cap),
_env_ram.dataspace_size(ram_cap));
Dma_buffer & buf = _dma_allocator.alloc_buffer(guard.ram_cap,
_env.pd().dma_addr(guard.ram_cap),
_env_ram.dataspace_size(guard.ram_cap));
guard.buf = &buf;
_domain_registry.for_each_domain([&] (Io_mmu::Domain & domain) {
domain.add_range({ buf.dma_addr, buf.size }, buf.phys_addr, buf.cap);
});
} catch (Out_of_ram) {
_env_ram.free(ram_cap);
throw;
} catch (Out_of_caps) {
_env_ram.free(ram_cap);
throw;
} catch (Dma_allocator::Out_of_virtual_memory) { }
return ram_cap;
guard.disarm();
return guard.ram_cap;
}