From 582da6527da30f6e21a95c9f3f2810d46a8f406e Mon Sep 17 00:00:00 2001 From: Thomas Petazzoni Date: Wed, 14 May 2014 13:36:36 +0200 Subject: [PATCH] of: make of_update_property() usable earlier in the boot process 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: ------------[ 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 [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [] (show_stack) from [] (dump_stack+0x84/0x94) [] (dump_stack) from [] (warn_slowpath_common+0x6c/0x88) [] (warn_slowpath_common) from [] (warn_slowpath_fmt+0x30/0x40) [] (warn_slowpath_fmt) from [] (kernfs_remove_by_name_ns+0x80/0x88) [] (kernfs_remove_by_name_ns) from [] (of_update_property+0xc0/0xf0) [] (of_update_property) from [] (mvebu_timer_and_clk_init+0xfc/0x194) [] (mvebu_timer_and_clk_init) from [] (start_kernel+0x218/0x350) [] (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 : [] lr : [] 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 [] (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 Fixes: 75b57ecf9d1d ("of: Make device nodes kobjects so they show up in sysfs") Signed-off-by: Grant Likely --- 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); -- 2.7.4