On Wed, 9 Aug 2023 at 07:08, Joel Stanley <joel@xxxxxxxxx> wrote: > > On Mon, 12 Jun 2023 at 19:57, Eddie James <eajames@xxxxxxxxxxxxx> 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. On hardware, it did this at FSI scan time: WARNING: CPU: 0 PID: 761 at /lib/idr.c:525 ida_free+0x140/0x154 ida_free called for id=1 which is not allocated. CPU: 0 PID: 761 Comm: openpower-proc- Not tainted 6.1.34-d42f59e #1 Hardware name: Generic DT based system unwind_backtrace from show_stack+0x18/0x1c show_stack from dump_stack_lvl+0x24/0x2c dump_stack_lvl from __warn+0x74/0xf0 __warn from warn_slowpath_fmt+0x9c/0xd8 warn_slowpath_fmt from ida_free+0x140/0x154 ida_free from fsi_master_register+0xd0/0xf0 fsi_master_register from hub_master_probe+0x11c/0x358 hub_master_probe from really_probe+0xd4/0x3f0 really_probe from driver_probe_device+0x38/0xd0 driver_probe_device from __device_attach_driver+0xc8/0x148 __device_attach_driver from bus_for_each_drv+0x90/0xdc bus_for_each_drv from __device_attach+0x114/0x1a4 __device_attach from bus_probe_device+0x8c/0x94 bus_probe_device from device_add+0x3a8/0x7fc device_add from fsi_master_scan+0x4e0/0x950 fsi_master_scan from fsi_master_rescan+0x38/0x88 fsi_master_rescan from master_rescan_store+0x14/0x20 master_rescan_store from kernfs_fop_write_iter+0x114/0x200 kernfs_fop_write_iter from vfs_write+0x1d0/0x374 vfs_write from ksys_write+0x78/0x100 ksys_write from ret_fast_syscall+0x0/0x54 Exception stack(0x9fc51fa8 to 0x9fc51ff0) 1fa0: 00000001 01a01c78 00000003 01a01c78 00000001 00000001 1fc0: 00000001 01a01c78 00000001 00000004 7eeb4ab0 7eeb4b3c 7eeb4ab4 7eeb499c 1fe0: 76985abc 7eeb4928 76848af8 766f176c > > > > > Signed-off-by: Eddie James <eajames@xxxxxxxxxxxxx> > > --- > > 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? > > > + 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? > > > + 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? > > > + master->idx = ida_alloc(&master_ida, GFP_KERNEL); > > + } > > + > > We check the same error condition again. > > > 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? > > > > - 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 > >