Messages in this thread | | | Date | Wed, 9 Aug 2023 11:21:05 -0500 | Subject | Re: [PATCH 11/14] fsi: Improve master indexing | From | Eddie James <> |
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On 8/9/23 02:08, Joel Stanley wrote: > On Mon, 12 Jun 2023 at 19:57, Eddie James <eajames@linux.ibm.com> wrote: >> Master indexing is problematic if a hub is rescanned while the >> root master is being rescanned. Move the IDA free below the device >> unregistration, lock the scan mutex in the probe function, and >> request a specific idx in the hub driver. > I've applied this series, but taking a closer look at this patch I > think it can be improved. If you resend, just send this patch. > >> Signed-off-by: Eddie James <eajames@linux.ibm.com> >> --- >> drivers/fsi/fsi-core.c | 41 ++++++++++++++++++++++-------------- >> drivers/fsi/fsi-master-hub.c | 2 ++ >> 2 files changed, 27 insertions(+), 16 deletions(-) >> >> diff --git a/drivers/fsi/fsi-core.c b/drivers/fsi/fsi-core.c >> index ec4d02264391..503061a6740b 100644 >> --- a/drivers/fsi/fsi-core.c >> +++ b/drivers/fsi/fsi-core.c >> @@ -1327,46 +1327,55 @@ static struct class fsi_master_class = { >> int fsi_master_register(struct fsi_master *master) >> { >> int rc; >> - struct device_node *np; >> >> mutex_init(&master->scan_lock); >> - master->idx = ida_alloc(&master_ida, GFP_KERNEL); >> + >> + if (master->idx) { > Why do we allocate a new idx if there's already one?
At this point, the master driver (aspeed, hub, i2cr, whatever) might just be requesting a certain index. It's not allocated yet, so it needs to be allocated so that we don't get overlap.
> >> + master->idx = ida_alloc_range(&master_ida, master->idx, >> + master->idx, GFP_KERNEL); > If we can't get one in the range we want, we ask for any? Should this > print a warning?
Perhaps, we could also return error here if we decide that the requested index is needed and not just wanted.
> >> + if (master->idx < 0) >> + master->idx = ida_alloc(&master_ida, GFP_KERNEL); >> + } else { > If ixd was zero, we create one. This is the "normal" case?
Yes, the assumption is: zero is the default due to zero-alloc'd master structures.
> >> + master->idx = ida_alloc(&master_ida, GFP_KERNEL); >> + } >> + > We check the same error condition again.
Yes I might be able to make this cleaner...
> >> if (master->idx < 0) >> return master->idx; >> - dev_set_name(&master->dev, "fsi%d", master->idx); >> + if (!dev_name(&master->dev)) >> + dev_set_name(&master->dev, "fsi%d", master->idx); >> + >> master->dev.class = &fsi_master_class; >> >> + mutex_lock(&master->scan_lock); >> rc = device_register(&master->dev); >> if (rc) { >> ida_free(&master_ida, master->idx); >> - return rc; >> - } >> + } else { >> + struct device_node *np = dev_of_node(&master->dev); > This change looks a bit different to the idx changes. What's happening here?
This is just restructuring to get the lock before the scan. It could be a separate commit, yea.
Thanks for the review!
Eddie
>> - np = dev_of_node(&master->dev); >> - if (!of_property_read_bool(np, "no-scan-on-init")) { >> - mutex_lock(&master->scan_lock); >> - fsi_master_scan(master); >> - mutex_unlock(&master->scan_lock); >> + if (!of_property_read_bool(np, "no-scan-on-init")) >> + fsi_master_scan(master); >> } >> >> - return 0; >> + mutex_unlock(&master->scan_lock); >> + return rc; >> } >> EXPORT_SYMBOL_GPL(fsi_master_register); >> >> void fsi_master_unregister(struct fsi_master *master) >> { >> - trace_fsi_master_unregister(master); >> + int idx = master->idx; >> >> - if (master->idx >= 0) { >> - ida_free(&master_ida, master->idx); >> - master->idx = -1; >> - } >> + trace_fsi_master_unregister(master); >> >> mutex_lock(&master->scan_lock); >> fsi_master_unscan(master); >> + master->n_links = 0; >> mutex_unlock(&master->scan_lock); >> + >> device_unregister(&master->dev); >> + ida_free(&master_ida, idx); >> } >> EXPORT_SYMBOL_GPL(fsi_master_unregister); >> >> diff --git a/drivers/fsi/fsi-master-hub.c b/drivers/fsi/fsi-master-hub.c >> index 6d8b6e8854e5..36da643b3201 100644 >> --- a/drivers/fsi/fsi-master-hub.c >> +++ b/drivers/fsi/fsi-master-hub.c >> @@ -12,6 +12,7 @@ >> #include <linux/slab.h> >> >> #include "fsi-master.h" >> +#include "fsi-slave.h" >> >> #define FSI_ENGID_HUB_MASTER 0x1c >> >> @@ -229,6 +230,7 @@ static int hub_master_probe(struct device *dev) >> hub->master.dev.release = hub_master_release; >> hub->master.dev.of_node = of_node_get(dev_of_node(dev)); >> >> + hub->master.idx = fsi_dev->slave->link + 1; >> hub->master.n_links = links; >> hub->master.read = hub_master_read; >> hub->master.write = hub_master_write; >> -- >> 2.31.1 >>
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