On Wed, 14 May 2014 13:36:36 +0200, Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxxxxxxxxx> wrote: > Commit 75b57ecf9d1d1e17d099ab13b8f48e6e038676be ('of: Make device > nodes kobjects so they show up in sysfs') has turned Device Tree nodes > in kobjects and added a sysfs based representation for Device Tree > nodes. Since the sysfs logic is only available after the execution of > a core_initcall(), the patch took precautions in of_add_property() and > of_remove_property() to not do any sysfs related manipulation early in > the boot process. > > However, it forgot to do the same for of_update_property(), which if > used early in the boot process (before core_initcalls have been > called), tries to call sysfs_remove_bin_file(), and crashes: Applied, thanks. g. > > ------------[ cut here ]------------ > WARNING: CPU: 0 PID: 0 at /home/thomas/projets/linux-2.6/fs/kernfs/dir.c:1216 kernfs_remove_by_name_ns+0x80/0x88() > kernfs: can not remove '(null)', no directory > Modules linked in: > CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.15.0-rc1-00127-g1d7e7b2-dirty #423 > [<c0014910>] (unwind_backtrace) from [<c00110ec>] (show_stack+0x10/0x14) > [<c00110ec>] (show_stack) from [<c04c84b8>] (dump_stack+0x84/0x94) > [<c04c84b8>] (dump_stack) from [<c001d8c0>] (warn_slowpath_common+0x6c/0x88) > [<c001d8c0>] (warn_slowpath_common) from [<c001d90c>] (warn_slowpath_fmt+0x30/0x40) > [<c001d90c>] (warn_slowpath_fmt) from [<c0104468>] (kernfs_remove_by_name_ns+0x80/0x88) > [<c0104468>] (kernfs_remove_by_name_ns) from [<c0394d98>] (of_update_property+0xc0/0xf0) > [<c0394d98>] (of_update_property) from [<c0647248>] (mvebu_timer_and_clk_init+0xfc/0x194) > [<c0647248>] (mvebu_timer_and_clk_init) from [<c0640934>] (start_kernel+0x218/0x350) > [<c0640934>] (start_kernel) from [<00008070>] (0x8070) > ---[ end trace 3406ff24bd97382e ]--- > Unable to handle kernel NULL pointer dereference at virtual address 0000003c > pgd = c0004000 > [0000003c] *pgd=00000000 > Internal error: Oops: 5 [#1] SMP ARM > Modules linked in: > CPU: 0 PID: 0 Comm: swapper/0 Tainted: G W 3.15.0-rc1-00127-g1d7e7b2-dirty #423 > task: c10ad4d8 ti: c10a2000 task.ti: c10a2000 > PC is at kernfs_find_ns+0x8/0xf0 > LR is at kernfs_find_and_get_ns+0x30/0x48 > pc : [<c0103834>] lr : [<c010394c>] psr: 600001d3 > sp : c10a3f34 ip : 00000073 fp : 00000000 > r10: 00000000 r9 : cfffc240 r8 : cfdf2980 > r7 : cf812c00 r6 : 00000000 r5 : 00000000 r4 : c10b45e0 > r3 : c10ad4d8 r2 : 00000000 r1 : cf812c00 r0 : 00000000 > Flags: nZCv IRQs off FIQs off Mode SVC_32 ISA ARM Segment kernel > Control: 10c53c7d Table: 0000404a DAC: 00000015 > Process swapper/0 (pid: 0, stack limit = 0xc10a2240) > Stack: (0xc10a3f34 to 0xc10a4000) > 3f20: c10b45e0 00000000 00000000 > 3f40: cf812c00 c010394c 00000063 cf812c00 00000001 cf812c00 cfdf29ac c03932cc > 3f60: 00000063 cf812bc0 cfdf29ac cf812c00 ffffffff c03943f8 cfdf2980 c0104468 > 3f80: cfdf2a04 cfdf2980 cf812bc0 c06634b0 c10aa3c0 c0394da4 c10f74dc cfdf2980 > 3fa0: cf812bc0 c0647248 c10aa3c0 ffffffff c10de940 c10aa3c0 ffffffff c0640934 > 3fc0: ffffffff ffffffff c06404ec 00000000 00000000 c06634b0 00000000 10c53c7d > 3fe0: c10aa434 c06634ac c10ae4c8 0000406a 414fc091 00008070 00000000 00000000 > [<c0103834>] (kernfs_find_ns) from [<00000001>] (0x1) > Code: e5c89001 eaffffcf e92d40f0 e1a06002 (e1d023bc) > ---[ end trace 3406ff24bd97382f ]--- > Kernel panic - not syncing: Attempted to kill the idle task! > ---[ end Kernel panic - not syncing: Attempted to kill the idle task! > > To fix this problem, we simply skip the sysfs related calls in > of_update_property(), and rely on of_init() to fix up things when it > will be called, exactly as is done in of_add_property() and > of_remove_property(). > > Signed-off-by: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxxxxxxxxx> > Fixes: 75b57ecf9d1d ("of: Make device nodes kobjects so they show up in sysfs") > --- > Changes since previous version: > - Use a ternary operator to bail out with the proper return value > instead of a goto. Requested by Rob Herring. > - Use a 12 digits hash and double quotes in the "Fixes:" > tag. Requested by Rob Herring. > - Rebased on top of 3.15-rc5 > > Signed-off-by: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxxxxxxxxx> > --- > drivers/of/base.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/of/base.c b/drivers/of/base.c > index 6d4ee22..32e969d 100644 > --- a/drivers/of/base.c > +++ b/drivers/of/base.c > @@ -1831,6 +1831,10 @@ int of_update_property(struct device_node *np, struct property *newprop) > if (!found) > return -ENODEV; > > + /* At early boot, bail out and defer setup to of_init() */ > + if (!of_kset) > + return found ? 0 : -ENODEV; > + > /* Update the sysfs attribute */ > sysfs_remove_bin_file(&np->kobj, &oldprop->attr); > __of_add_property_sysfs(np, newprop); > -- > 1.9.3 > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html