Messages in this thread | ![/](/images/icornerl.gif) | | From | Eric Curtin <> | Date | Wed, 14 Dec 2022 14:43:48 +0000 | Subject | Re: [PATCH] nvmem: core: Fix race in nvmem_register() |
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On Wed, 14 Dec 2022 at 14:40, Hector Martin <marcan@marcan.st> wrote: > > nvmem_register() currently registers the device before adding the nvmem > cells, which creates a race window where consumers may find the nvmem > device (and not get PROBE_DEFERred), but then fail to find the cells and > error out. > > Move device registration to the end of nvmem_register(), to close the > race. > > Observed when the stars line up on Apple Silicon machines with the (not > yet upstream, but trivial) spmi nvmem driver and the macsmc-rtc client: > > [ 0.487375] macsmc-rtc macsmc-rtc: error -ENOENT: Failed to get rtc_offset NVMEM cell > > Fixes: eace75cfdcf7 ("nvmem: Add a simple NVMEM framework for nvmem providers") > Signed-off-by: Hector Martin <marcan@marcan.st>
Reviewed-by: Eric Curtin <ecurtin@redhat.com>
> --- > drivers/nvmem/core.c | 18 ++++++++---------- > 1 file changed, 8 insertions(+), 10 deletions(-) > > diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c > index 321d7d63e068..d255feca5e17 100644 > --- a/drivers/nvmem/core.c > +++ b/drivers/nvmem/core.c > @@ -837,20 +837,16 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) > > dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name); > > - rval = device_register(&nvmem->dev); > - if (rval) > - goto err_put_device; > - > if (nvmem->nkeepout) { > rval = nvmem_validate_keepouts(nvmem); > if (rval) > - goto err_device_del; > + return ERR_PTR(rval); > } > > if (config->compat) { > rval = nvmem_sysfs_setup_compat(nvmem, config); > if (rval) > - goto err_device_del; > + return ERR_PTR(rval); > } > > if (config->cells) { > @@ -867,19 +863,21 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) > if (rval) > goto err_remove_cells; > > + rval = device_register(&nvmem->dev); > + if (rval) > + goto err_put_device; > + > blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem); > > return nvmem; > > +err_put_device: > + put_device(&nvmem->dev); > err_remove_cells: > nvmem_device_remove_all_cells(nvmem); > err_teardown_compat: > if (config->compat) > nvmem_sysfs_remove_compat(nvmem, config); > -err_device_del: > - device_del(&nvmem->dev); > -err_put_device: > - put_device(&nvmem->dev); > > return ERR_PTR(rval); > } > -- > 2.35.1 > >
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