powerpc/mm/ptdump: Wrap seq_printf() to handle NULL pointers

Lovingly borrowed from the arch/arm64 ptdump code.

This doesn't seem to be an issue in practice, but is necessary for my
upcoming commit.

Signed-off-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/mm/ptdump/ptdump.c b/arch/powerpc/mm/ptdump/ptdump.c
index 48135ba..e249a56 100644 (file)
--- a/arch/powerpc/mm/ptdump/ptdump.c
+++ b/arch/powerpc/mm/ptdump/ptdump.c
@@ -108,6 +108,18 @@ static struct addr_marker address_markers[] = {
        { -1,   NULL },
 };
 
+#define pt_dump_seq_printf(m, fmt, args...)    \
+({                                             \
+       if (m)                                  \
+               seq_printf(m, fmt, ##args);     \
+})
+
+#define pt_dump_seq_putc(m, c)         \
+({                                     \
+       if (m)                          \
+               seq_putc(m, c);         \
+})
+
 static void dump_flag_info(struct pg_state *st, const struct flag_info
                *flag, u64 pte, int num)
 {
@@ -125,19 +137,19 @@ static void dump_flag_info(struct pg_state *st, const struct flag_info
                        val = pte & flag->val;
                        if (flag->shift)
                                val = val >> flag->shift;
-                       seq_printf(st->seq, "  %s:%llx", flag->set, val);
+                       pt_dump_seq_printf(st->seq, "  %s:%llx", flag->set, val);
                } else {
                        if ((pte & flag->mask) == flag->val)
                                s = flag->set;
                        else
                                s = flag->clear;
                        if (s)
-                               seq_printf(st->seq, "  %s", s);
+                               pt_dump_seq_printf(st->seq, "  %s", s);
                }
                st->current_flags &= ~flag->mask;
        }
        if (st->current_flags != 0)
-               seq_printf(st->seq, "  unknown flags:%llx", st->current_flags);
+               pt_dump_seq_printf(st->seq, "  unknown flags:%llx", st->current_flags);
 }
 
 static void dump_addr(struct pg_state *st, unsigned long addr)
@@ -152,12 +164,12 @@ static void dump_addr(struct pg_state *st, unsigned long addr)
 #define REG            "0x%08lx"
 #endif
 
-       seq_printf(st->seq, REG "-" REG " ", st->start_address, addr - 1);
+       pt_dump_seq_printf(st->seq, REG "-" REG " ", st->start_address, addr - 1);
        if (st->start_pa == st->last_pa && st->start_address + PAGE_SIZE != addr) {
-               seq_printf(st->seq, "[" REG "]", st->start_pa);
+               pt_dump_seq_printf(st->seq, "[" REG "]", st->start_pa);
                delta = PAGE_SIZE >> 10;
        } else {
-               seq_printf(st->seq, " " REG " ", st->start_pa);
+               pt_dump_seq_printf(st->seq, " " REG " ", st->start_pa);
                delta = (addr - st->start_address) >> 10;
        }
        /* Work out what appropriate unit to use */
@@ -165,7 +177,7 @@ static void dump_addr(struct pg_state *st, unsigned long addr)
                delta >>= 10;
                unit++;
        }
-       seq_printf(st->seq, "%9lu%c", delta, *unit);
+       pt_dump_seq_printf(st->seq, "%9lu%c", delta, *unit);
 
 }
 
@@ -182,7 +194,7 @@ static void note_page(struct pg_state *st, unsigned long addr,
                st->start_address = addr;
                st->start_pa = pa;
                st->last_pa = pa;
-               seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
+               pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
        /*
         * Dump the section of virtual memory when:
         *   - the PTE flags from one entry to the next differs.
@@ -206,7 +218,7 @@ static void note_page(struct pg_state *st, unsigned long addr,
                                          st->current_flags,
                                          pg_level[st->level].num);
 
-                       seq_putc(st->seq, '\n');
+                       pt_dump_seq_putc(st->seq, '\n');
                }
 
                /*
@@ -215,7 +227,7 @@ static void note_page(struct pg_state *st, unsigned long addr,
                 */
                while (addr >= st->marker[1].start_address) {
                        st->marker++;
-                       seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
+                       pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
                }
                st->start_address = addr;
                st->start_pa = pa;