kconfig: silence warning when parsing auto.conf when a symbol has changed type

When a symbol changes type from tristate to bool, and was previously set to
'm', a subsequent silentoldconfig would warn about inconsistency, such as:

    include/config/auto.conf:3014:warning: symbol value 'm' invalid for
    HOTPLUG_PCI_PCIE

Seen by Linus with the merge in aa8032b (sequence to reproduce by Michal):
    git checkout 1fe0135
    make mrproper
    make allmodconfig
    make silentoldconfig
    git checkout aa8032b
    make allmodconfig
    make silentoldconfig

Since HOTPLUG_PCI_PCIE changed from tristate to bool in aa8032b, it was
previously set to 'm' in auto.conf by the first allmodconfig+silentoldconfig,
but then was set to 'y' by the second allmodconfig. Then the second
silentoldconfig prints the warning.

The warning in this case is a spurious warning, which happens at the time
kconfig tries to detect symbols that have changed, to touch the empty
header files in include/config used for dependency-tracking by make.

Silence the warning when we read the old auto.conf file, since it is
perfectly legit that a symbol changed type since the previous call.

Thread in:
    http://marc.info/?l=linux-pci&m=137569198904000&w=2

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>

diff --git a/config/confdata.c b/config/confdata.c
index 8128254a6265626e1f89efdec27d6ea06b830ea1..a856c19c1cbc813fe1ae9bb22dfa04941f9be143 100644 (file)
--- a/config/confdata.c
+++ b/config/confdata.c
@@ -140,7 +140,9 @@ static int conf_set_sym_val(struct symbol *sym, int def, int def_flags, char *p)
                        sym->flags |= def_flags;
                        break;
                }
-               conf_warning("symbol value '%s' invalid for %s", p, sym->name);
+               if (def != S_DEF_AUTO)
+                       conf_warning("symbol value '%s' invalid for %s",
+                                    p, sym->name);
                return 1;
        case S_OTHER:
                if (*p != '"') {
@@ -161,7 +163,8 @@ static int conf_set_sym_val(struct symbol *sym, int def, int def_flags, char *p)
                        memmove(p2, p2 + 1, strlen(p2));
                }
                if (!p2) {
-                       conf_warning("invalid string found");
+                       if (def != S_DEF_AUTO)
+                               conf_warning("invalid string found");
                        return 1;
                }
                /* fall through */
@@ -172,7 +175,9 @@ static int conf_set_sym_val(struct symbol *sym, int def, int def_flags, char *p)
                        sym->def[def].val = strdup(p);
                        sym->flags |= def_flags;
                } else {
-                       conf_warning("symbol value '%s' invalid for %s", p, sym->name);
+                       if (def != S_DEF_AUTO)
+                               conf_warning("symbol value '%s' invalid for %s",
+                                            p, sym->name);
                        return 1;
                }
                break;