[PATCH v3] kconfig: make unmet dependency warnings readable

From: Masahiro Yamada
Date: Sat Mar 10 2018 - 10:54:41 EST


Currently, the unmet dependency warnings end up with endlessly long
expressions, most of which are false positives.

Here is test code to demonstrate how it currently works.

[Test Case]

config DEP1
def_bool y

config DEP2
bool "DEP2"

config A
bool "A"
select E

config B
bool "B"
depends on DEP2
select E

config C
bool "C"
depends on DEP1 && DEP2
select E

config D
def_bool n
select E

config E
bool
depends on DEP1 && DEP2

[Result]

$ make config
scripts/kconfig/conf --oldaskconfig Kconfig
*
* Linux Kernel Configuration
*
DEP2 (DEP2) [N/y/?] (NEW) n
A (A) [N/y/?] (NEW) y
warning: (A && B && D) selects E which has unmet direct
dependencies (DEP1 && DEP2)

Here, I see some points to be improved.

First, '(A || B || D)' would make more sense than '(A && B && D)'.
I am not sure if this is intentional, but expr_simplify_unmet_dep()
turns OR expressions into AND, like follows:

case E_OR:
return expr_alloc_and(

Second, we see false positives. 'A' is a real unmet dependency.
'B' is false positive because 'DEP1' is fixed to 'y', and 'B' depends
on 'DEP2'. 'C' was correctly dropped by expr_simplify_unmet_dep().
'D' is also false positive because it has no chance to be enabled.
Current expr_simplify_unmet_dep() cannot avoid those false positives.

After all, I decided to use the same helpers as used for printing
reverse dependencies in the help.

With this commit, unreadable warnings in the real world:

$ make ARCH=score allyesconfig
scripts/kconfig/conf --allyesconfig Kconfig
warning: (HWSPINLOCK_QCOM && AHCI_MTK && STMMAC_PLATFORM && DWMAC_IPQ806X
&& DWMAC_LPC18XX && DWMAC_OXNAS && DWMAC_ROCKCHIP && DWMAC_SOCFPGA && DWMA
C_STI && TI_CPSW && PINCTRL_GEMINI && PINCTRL_OXNAS && PINCTRL_ROCKCHIP &&
PINCTRL_DOVE && PINCTRL_ARMADA_37XX && PINCTRL_STM32 && S3C2410_WATCHDOG
&& VIDEO_OMAP3 && VIDEO_S5P_FIMC && USB_XHCI_MTK && RTC_DRV_AT91SAM9 && LP
C18XX_DMAMUX && VIDEO_OMAP4 && COMMON_CLK_GEMINI && COMMON_CLK_ASPEED && C
OMMON_CLK_NXP && COMMON_CLK_OXNAS && COMMON_CLK_BOSTON && ATMEL_ST && QCOM
_ADSP_PIL && QCOM_Q6V5_PIL && QCOM_GSBI && ATMEL_EBI && ST_IRQCHIP && RESE
T_IMX7 && PHY_HI6220_USB && PHY_RALINK_USB && PHY_ROCKCHIP_PCIE && PHY_DA8
XX_USB) selects MFD_SYSCON which has unmet direct dependencies (HAS_IOMEM)
warning: (PINCTRL_AT91 && PINCTRL_AT91PIO4 && PINCTRL_OXNAS && PINCTRL_PIS
TACHIO && PINCTRL_PIC32 && PINCTRL_MESON && PINCTRL_NOMADIK && PINCTRL_MTK
&& PINCTRL_MT7622 && GPIO_TB10X) selects OF_GPIO which has unmet direct d
ependencies (GPIOLIB && OF && HAS_IOMEM)
warning: (FAULT_INJECTION_STACKTRACE_FILTER && LATENCYTOP && LOCKDEP) sele
cts FRAME_POINTER which has unmet direct dependencies (DEBUG_KERNEL && (CR
IS || M68K || FRV || UML || SUPERH || BLACKFIN || MN10300 || METAG) || ARC
H_WANT_FRAME_POINTERS)

will be turned into:

$ make ARCH=score allyesconfig
scripts/kconfig/conf --allyesconfig Kconfig

WARNING: unmet direct dependencies detected for MFD_SYSCON
Depends on:
HAS_IOMEM [=n]
Selected by [y]:
- PINCTRL_STM32 [=y] && PINCTRL [=y] && (ARCH_STM32 || COMPILE_TEST [=y])
&& OF [=y]
- RTC_DRV_AT91SAM9 [=y] && RTC_CLASS [=y] && (ARCH_AT91 || COMPILE_TEST
[=y])
- ATMEL_ST [=y] && GENERIC_CLOCKEVENTS [=y]
- RESET_IMX7 [=y] && RESET_CONTROLLER [=y]
- PHY_HI6220_USB [=y] && (ARCH_HISI && ARM64 || COMPILE_TEST [=y])
- PHY_RALINK_USB [=y] && (RALINK || COMPILE_TEST [=y])
- PHY_ROCKCHIP_PCIE [=y] && (ARCH_ROCKCHIP && OF [=y] || COMPILE_TEST
[=y])

WARNING: unmet direct dependencies detected for OF_GPIO
Depends on:
GPIOLIB [=y] && OF [=y] && HAS_IOMEM [=n]
Selected by [y]:
- PINCTRL_MTK [=y] && PINCTRL [=y] && (ARCH_MEDIATEK || COMPILE_TEST
[=y]) && OF [=y]
- PINCTRL_MT7622 [=y] && PINCTRL [=y] && (ARCH_MEDIATEK || COMPILE_TEST
[=y]) && OF [=y] && (ARM64 || COMPILE_TEST [=y])

WARNING: unmet direct dependencies detected for FRAME_POINTER
Depends on:
DEBUG_KERNEL [=y] && (CRIS || M68K || FRV || UML || SUPERH || BLACKFIN
|| MN10300 || METAG) || ARCH_WANT_FRAME_POINTERS [=n]
Selected by [y]:
- LATENCYTOP [=y] && DEBUG_KERNEL [=y] && STACKTRACE_SUPPORT [=y] &&
PROC_FS [=y] && !MIPS && !PPC && !S390 && !MICROBLAZE && !ARM_UNWIND &&
!ARC && !X86

Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
Reviewed-by: Petr Vorel <petr.vorel@xxxxxxxxx>
---

Changes in v3:
- Remove unused expr_get_leftmost_symbol()
- Move error message to the same line as 'WARNING'
- update test case

Changes in v2:
- update test case

scripts/kconfig/expr.c | 42 ------------------------------------------
scripts/kconfig/expr.h | 1 -
scripts/kconfig/symbol.c | 34 ++++++++++++++++++++++------------
3 files changed, 22 insertions(+), 55 deletions(-)

diff --git a/scripts/kconfig/expr.c b/scripts/kconfig/expr.c
index 49376e1..e1a39e9 100644
--- a/scripts/kconfig/expr.c
+++ b/scripts/kconfig/expr.c
@@ -1137,48 +1137,6 @@ static int expr_compare_type(enum expr_type t1, enum expr_type t2)
return 0;
}

-static inline struct expr *
-expr_get_leftmost_symbol(const struct expr *e)
-{
-
- if (e == NULL)
- return NULL;
-
- while (e->type != E_SYMBOL)
- e = e->left.expr;
-
- return expr_copy(e);
-}
-
-/*
- * Given expression `e1' and `e2', returns the leaf of the longest
- * sub-expression of `e1' not containing 'e2.
- */
-struct expr *expr_simplify_unmet_dep(struct expr *e1, struct expr *e2)
-{
- struct expr *ret;
-
- switch (e1->type) {
- case E_OR:
- return expr_alloc_and(
- expr_simplify_unmet_dep(e1->left.expr, e2),
- expr_simplify_unmet_dep(e1->right.expr, e2));
- case E_AND: {
- struct expr *e;
- e = expr_alloc_and(expr_copy(e1), expr_copy(e2));
- e = expr_eliminate_dups(e);
- ret = (!expr_eq(e, e1)) ? e1 : NULL;
- expr_free(e);
- break;
- }
- default:
- ret = e1;
- break;
- }
-
- return expr_get_leftmost_symbol(ret);
-}
-
void expr_print(struct expr *e,
void (*fn)(void *, struct symbol *, const char *),
void *data, int prevtoken)
diff --git a/scripts/kconfig/expr.h b/scripts/kconfig/expr.h
index 8dbf2a4..94a383b 100644
--- a/scripts/kconfig/expr.h
+++ b/scripts/kconfig/expr.h
@@ -305,7 +305,6 @@ struct expr *expr_transform(struct expr *e);
int expr_contains_symbol(struct expr *dep, struct symbol *sym);
bool expr_depends_symbol(struct expr *dep, struct symbol *sym);
struct expr *expr_trans_compare(struct expr *e, enum expr_type type, struct symbol *sym);
-struct expr *expr_simplify_unmet_dep(struct expr *e1, struct expr *e2);

void expr_fprint(struct expr *e, FILE *out);
struct gstr; /* forward */
diff --git a/scripts/kconfig/symbol.c b/scripts/kconfig/symbol.c
index 0f7eba7..8b13c16 100644
--- a/scripts/kconfig/symbol.c
+++ b/scripts/kconfig/symbol.c
@@ -333,6 +333,26 @@ static struct symbol *sym_calc_choice(struct symbol *sym)
return def_sym;
}

+static void sym_warn_unmet_dependency(struct symbol *sym)
+{
+ struct gstr gs = str_new();
+
+ str_printf(&gs,
+ "\nWARNING: unmet direct dependencies detected for %s\n"
+ " Depends on:\n"
+ " ",
+ sym->name);
+ expr_gstr_print(sym->dir_dep.expr, &gs);
+ str_printf(&gs, "\n");
+
+ expr_gstr_print_revdep(sym->rev_dep.expr, &gs, yes,
+ " Selected by [y]:\n");
+ expr_gstr_print_revdep(sym->rev_dep.expr, &gs, mod,
+ " Selected by [m]:\n");
+
+ fputs(str_get(&gs), stderr);
+}
+
void sym_calc_value(struct symbol *sym)
{
struct symbol_value newval, oldval;
@@ -414,18 +434,8 @@ void sym_calc_value(struct symbol *sym)
}
}
calc_newval:
- if (sym->dir_dep.tri == no && sym->rev_dep.tri != no) {
- struct expr *e;
- e = expr_simplify_unmet_dep(sym->rev_dep.expr,
- sym->dir_dep.expr);
- fprintf(stderr, "warning: (");
- expr_fprint(e, stderr);
- fprintf(stderr, ") selects %s which has unmet direct dependencies (",
- sym->name);
- expr_fprint(sym->dir_dep.expr, stderr);
- fprintf(stderr, ")\n");
- expr_free(e);
- }
+ if (sym->dir_dep.tri == no && sym->rev_dep.tri != no)
+ sym_warn_unmet_dependency(sym);
newval.tri = EXPR_OR(newval.tri, sym->rev_dep.tri);
}
if (newval.tri == mod &&
--
2.7.4