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| author | Vlastimil Babka <vbabka@suse.cz> | 2021-02-25 17:46:39 +0100 |
|---|---|---|
| committer | Petr Mladek <pmladek@suse.com> | 2021-04-07 13:20:59 +0200 |
| commit | a48849e2358ecf1a347a03b33dc27b9b2f25f8fd (patch) | |
| tree | f47ee70b3fb98b2b99b5ac451a4d480bbdbbb132 /lib/vsprintf.c | |
| parent | MAINTAINERS: update Senozhatsky email address (diff) | |
| download | linux-a48849e2358ecf1a347a03b33dc27b9b2f25f8fd.tar.xz linux-a48849e2358ecf1a347a03b33dc27b9b2f25f8fd.zip | |
printk: clarify the documentation for plain pointer printing
We have several modifiers for plain pointers (%p, %px and %pK) and now
also the no_hash_pointers boot parameter. The documentation should help
to choose which variant to use. Importantly, we should discourage %px
in favor of %p (with the new boot parameter when debugging), and stress
that %pK should be only used for procfs and similar files, not dmesg
buffer. This patch clarifies the documentation in that regard.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20210225164639.27212-1-vbabka@suse.cz
Diffstat (limited to '')
| -rw-r--r-- | lib/vsprintf.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 4a14889ccb35..5ec8ad238d03 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -2189,7 +2189,9 @@ early_param("no_hash_pointers", no_hash_pointers_enable); * Implements a "recursive vsnprintf". * Do not use this feature without some mechanism to verify the * correctness of the format string and va_list arguments. - * - 'K' For a kernel pointer that should be hidden from unprivileged users + * - 'K' For a kernel pointer that should be hidden from unprivileged users. + * Use only for procfs, sysfs and similar files, not printk(); please + * read the documentation (path below) first. * - 'NF' For a netdev_features_t * - 'h[CDN]' For a variable-length buffer, it prints it as a hex string with * a certain separator (' ' by default): @@ -2228,7 +2230,8 @@ early_param("no_hash_pointers", no_hash_pointers_enable); * Without an option prints the full name of the node * f full name * P node name, including a possible unit address - * - 'x' For printing the address. Equivalent to "%lx". + * - 'x' For printing the address unmodified. Equivalent to "%lx". + * Please read the documentation (path below) before using! * - '[ku]s' For a BPF/tracing related format specifier, e.g. used out of * bpf_trace_printk() where [ku] prefix specifies either kernel (k) * or user (u) memory to probe, and: |