Re: [PATCH v2] pstore: Support already existing reserved-memory node

[Daniel Golle <daniel@makrotopia.org>]

Hi Detlev,

On Tue, Apr 19, 2022 at 09:58:00AM -0400, Detlev Casanova wrote:
> Hey Daniel,
> 
> I see that the node is called ramoops@0x42ff0000. We usually don't set the 0x 
> in device tree nodes, and that's why the fdt_add_subnode function doesn't see 
> it and add ramoops@42ff0000 (it just compares the text). For Linux, both nodes 
> are the same and it complains.
> 
> I think the best course of action here is to remove that '0x' in your dts, so 
> that u-boot sees it as the pstore node.

I tried the change you suggest and remove the '0x' prefix and indeed that
works, the lengthy kernel warning about duplicate nodes and sysfs
entries are gone and pstore works as expected.
I've hence committed that change to OpenWrt:

https://git.openwrt.org/?p=openwrt/openwrt.git;a=commit;h=fc245338d6e02e61fa7ecbd1a828aed97cdbef88

However, now there is another error message in U-Boot output:
Add 'ramoops@42ff0000' node failed: FDT_ERR_EXISTS

I figured that this is not a problem as previously (ie. before your
patch) even the exitence of the 'reserved-memory' node would result in
the 'ramoops' node not being added while now it really just errors out
in case of exactly that 'ramoops' node already existing, which is fine.

Thank you again for resolving this issue!


Cheers


Daniel


> 
> Regards,
> 
> Detlev.
> 
> On Monday, April 18, 2022 7:50:36 P.M. EDT Daniel Golle wrote:
> > Hi Detlev,
> > 
> > On Mon, Apr 18, 2022 at 02:46:21PM -0400, Detlev Casanova wrote:
> > > Hi Daniel,
> > > 
> > > The patch only checks the existence of the reserved-memory node.
> > > 
> > > I guess that before, adding the reserved-memory node failed and so nothing
> > > else was happening. Now, the node is found and then, it adds the ramoops
> > > subnode to it, making it double because it is already there in your case.
> > > 
> > > But that should not happen, because the fdt_add_subnode() function should
> > > fail if the node is already present (like it was failing for
> > > reserved-memory).
> > > 
> > > I'm going to look into it. Can you send me the device tree taht you are
> > > using (or at least the reserved-memory part) and u-boot config ?
> > 
> > Thank you for your reply and for taking a look at what's going on.
> > 
> > reserved-memory bits in dts:
> > https://git.openwrt.org/?p=openwrt/openwrt.git;a=blob;f=package/boot/uboot-m
> > ediatek/patches/050-mt7622-enable-pstore.patch
> > 
> > u-boot config:
> > https://git.openwrt.org/?p=openwrt/openwrt.git;a=blob;f=package/boot/uboot-m
> > ediatek/patches/404-add-bananapi_bpi-r64_defconfigs.patch
> > 
> > 
> > Cheers
> > 
> > 
> > Daniel
> > 
> > > Detlev.
> > > 
> > > On Monday, April 11, 2022 7:00:20 P.M. EDT Daniel Golle wrote:
> > > > Hi Detlev,
> > > > 
> > > > I've recently tried to update U-Boot from 2022.01 to 2022.04 and
> > > > noticed a regression introduced by the commit below.
> > > > 
> > > > While the unwanted error message ("Add 'reserved-memory' node failed:
> > > > FDT_ERR_EXISTS") no longer appears, I now see a lengthy kernel stack
> > > > trace in Linux instead:
> > > > ...
> > > > [    0.008295] sysfs: cannot create duplicate filename
> > > > '/devices/platform/42ff0000.ramoops' [    0.008303] CPU: 0 PID: 1 Comm:
> > > > swapper/0 Tainted: G S                5.15.33 #0 [    0.008312] Hardware
> > > > name: Bananapi BPI-R64 (DT)
> > > > [    0.008318] Call trace:
> > > > [    0.008322]  dump_backtrace+0x0/0x15c
> > > > [    0.008337]  show_stack+0x14/0x30
> > > > [    0.008345]  dump_stack_lvl+0x64/0x7c
> > > > [    0.008355]  dump_stack+0x14/0x2c
> > > > [    0.008362]  sysfs_warn_dup+0x5c/0x74
> > > > [    0.008373]  sysfs_create_dir_ns+0xb0/0xc0
> > > > [    0.008381]  kobject_add_internal+0xbc/0x330
> > > > [    0.008392]  kobject_add+0x80/0xe0
> > > > [    0.008400]  device_add+0xd4/0x82c
> > > > [    0.008410]  of_device_add+0x4c/0x5c
> > > > [    0.008420]  of_platform_device_create_pdata+0xb8/0xf0
> > > > [    0.008428]  of_platform_default_populate_init+0x58/0xcc
> > > > [    0.008437]  do_one_initcall+0x4c/0x1b0
> > > > [    0.008444]  kernel_init_freeable+0x230/0x294
> > > > [    0.008456]  kernel_init+0x20/0x120
> > > > [    0.008463]  ret_from_fork+0x10/0x20
> > > > [    0.008471] kobject_add_internal failed for 42ff0000.ramoops with
> > > > -EEXIST, don't try to register things with the same name in the same
> > > > directory. ...
> > > > 
> > > > I assume that fdt_find_or_add_subnode() doesn't behave as expected and
> > > > apparently adds a duplicate node having the same name.
> > > > The pstore/ramoops reserved-memory is already defined in the fdt
> > > > contained in the FIT image (for compatibility with older U-Boot which
> > > > didn't care about pstore), so it should be not added again.
> > > > 
> > > > On Mon, Feb 07, 2022 at 11:02:30AM -0500, Detlev Casanova wrote:
> > > > > The pstore command tries to create a reserved-memory node but fails if
> > > > > 
> > > > > it is already present with:
> > > > >     Add 'reserved-memory' node failed: FDT_ERR_EXISTS
> > > > > 
> > > > > This patch creates the node only if it does not exist and adapts the
> > > > > reg
> > > > > values sizes depending on already present #address-cells and
> > > > > #size-cells
> > > > > values.
> > > > > 
> > > > > Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com>
> > > > > ---
> > > > > 
> > > > > Changes in v2:
> > > > >  - Move declarations at beginning of function
> > > > >  - Use if instead of switch
> > > > >  - Reword Subject
> > > > >  
> > > > >  cmd/pstore.c | 39 ++++++++++++++++++++++++++++++++++-----
> > > > >  1 file changed, 34 insertions(+), 5 deletions(-)
> > > > > 
> > > > > diff --git a/cmd/pstore.c b/cmd/pstore.c
> > > > > index 9fac8c7218..cd6f6feb2f 100644
> > > > > --- a/cmd/pstore.c
> > > > > +++ b/cmd/pstore.c
> > > > > @@ -11,6 +11,7 @@
> > > > > 
> > > > >  #include <mapmem.h>
> > > > >  #include <memalign.h>
> > > > >  #include <part.h>
> > > > > 
> > > > > +#include <fdt_support.h>
> > > > > 
> > > > >  struct persistent_ram_buffer {
> > > > >  
> > > > >  	u32    sig;
> > > > > 
> > > > > @@ -485,6 +486,8 @@ void fdt_fixup_pstore(void *blob)
> > > > > 
> > > > >  {
> > > > >  
> > > > >  	char node[32];
> > > > >  	int  nodeoffset;	/* node offset from libfdt */
> > > > > 
> > > > > +	u32 addr_cells;
> > > > > +	u32 size_cells;
> > > > > 
> > > > >  	nodeoffset = fdt_path_offset(blob, "/");
> > > > >  	if (nodeoffset < 0) {
> > > > > 
> > > > > @@ -493,14 +496,18 @@ void fdt_fixup_pstore(void *blob)
> > > > > 
> > > > >  		return;
> > > > >  	
> > > > >  	}
> > > > > 
> > > > > -	nodeoffset = fdt_add_subnode(blob, nodeoffset, "reserved-memory");
> > > > > +	nodeoffset = fdt_find_or_add_subnode(blob, nodeoffset,
> > > > > "reserved-memory");>
> > > > > 
> > > > >  	if (nodeoffset < 0) {
> > > > >  	
> > > > >  		log_err("Add 'reserved-memory' node failed: %s\n",
> > > > >  		
> > > > >  				fdt_strerror(nodeoffset));
> > > > >  		
> > > > >  		return;
> > > > >  	
> > > > >  	}
> > > > > 
> > > > > -	fdt_setprop_u32(blob, nodeoffset, "#address-cells", 2);
> > > > > -	fdt_setprop_u32(blob, nodeoffset, "#size-cells", 2);
> > > > > +
> > > > > +	addr_cells = fdt_getprop_u32_default_node(blob, nodeoffset, 0,
> > > > > "#address-cells", 2); +	size_cells =
> > > > > fdt_getprop_u32_default_node(blob,
> > > > > nodeoffset, 0, "#size-cells", 2); +	fdt_setprop_u32(blob, nodeoffset,
> > > > > "#address-cells", addr_cells); +	fdt_setprop_u32(blob, nodeoffset,
> > > > > "#size-cells", size_cells);
> > > > > +
> > > > > 
> > > > >  	fdt_setprop_empty(blob, nodeoffset, "ranges");
> > > > >  	
> > > > >  	sprintf(node, "ramoops@%llx", (unsigned long long)pstore_addr);
> > > > > 
> > > > > @@ -509,14 +516,36 @@ void fdt_fixup_pstore(void *blob)
> > > > > 
> > > > >  		log_err("Add '%s' node failed: %s\n", node,
> > > 
> > > fdt_strerror(nodeoffset));
> > > 
> > > > >  		return;
> > > > >  	
> > > > >  	}
> > > > > 
> > > > > +
> > > > > 
> > > > >  	fdt_setprop_string(blob, nodeoffset, "compatible", "ramoops");
> > > > > 
> > > > > -	fdt_setprop_u64(blob, nodeoffset, "reg", pstore_addr);
> > > > > -	fdt_appendprop_u64(blob, nodeoffset, "reg", pstore_length);
> > > > > +
> > > > > +	if (addr_cells == 1) {
> > > > > +		fdt_setprop_u32(blob, nodeoffset, "reg", pstore_addr);
> > > > > +	} else if (addr_cells == 2) {
> > > > > +		fdt_setprop_u64(blob, nodeoffset, "reg", pstore_addr);
> > > > > +	} else {
> > > > > +		log_err("Unsupported #address-cells: %u\n",
> > > 
> > > addr_cells);
> > > 
> > > > > +		goto clean_ramoops;
> > > > > +	}
> > > > > +
> > > > > +	if (size_cells == 1) {
> > > > > +		// Let's consider that the pstore_length fits in a 32
> > > 
> > > bits value
> > > 
> > > > > +		fdt_appendprop_u32(blob, nodeoffset, "reg",
> > > 
> > > pstore_length);
> > > 
> > > > > +	} else if (size_cells == 2) {
> > > > > +		fdt_appendprop_u64(blob, nodeoffset, "reg",
> > > 
> > > pstore_length);
> > > 
> > > > > +	} else {
> > > > > +		log_err("Unsupported #size-cells: %u\n", addr_cells);
> > > > > +		goto clean_ramoops;
> > > > > +	}
> > > > > +
> > > > > 
> > > > >  	fdt_setprop_u32(blob, nodeoffset, "record-size",
> > > 
> > > pstore_record_size);
> > > 
> > > > >  	fdt_setprop_u32(blob, nodeoffset, "console-size",
> > > 
> > > pstore_console_size);
> > > 
> > > > >  	fdt_setprop_u32(blob, nodeoffset, "ftrace-size",
> > > 
> > > pstore_ftrace_size);
> > > 
> > > > >  	fdt_setprop_u32(blob, nodeoffset, "pmsg-size", pstore_pmsg_size);
> > > > >  	fdt_setprop_u32(blob, nodeoffset, "ecc-size", pstore_ecc_size);
> > > > > 
> > > > > +
> > > > > +clean_ramoops:
> > > > > +	fdt_del_node_and_alias(blob, node);
> > > > > 
> > > > >  }
> > > > >  
> > > > >  U_BOOT_CMD(pstore, 10, 0, do_pstore,
> 
> 
> 
>