[PATCH] makedumpfile: close the dwfl handle before next invocation of init_dwarf_info()
Atsushi Kumagai
kumagai-atsushi at mxc.nes.nec.co.jp
Wed Apr 17 20:46:50 EDT 2013
Hello Mahesh,
On Mon, 15 Apr 2013 15:50:52 +0530
Mahesh J Salgaonkar <mahesh at linux.vnet.ibm.com> wrote:
> From: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>
>
> The init_dwarf_info() function initializes "dwarf_info.dwfl" handle everytime
> when it is called. The "dwarf_info.dwfl" handle should be freed once we are
> done with searching of desired debuginfo and before next invocation of
> init_dwarf_info().
>
> Most of the functions (e.g get_debug_info()) that invokes init_dwarf_info()
> also invokes clean_dwfl_info() to free dwfl handle. But the function
> get_die_from_offset() that invokes init_dwarf_info(), does not free the dwfl
> handle and hence it keeps re-reading debuginfo ELF section into memory every
> time it is invoked until it starts failing with following errors:
>
> init_dwarf_info: Can't get first elf header of /usr/lib/debug/boot/vmlinux-x.x.x
> get_die_attr_type: Can't find the DIE.
> init_dwarf_info: Can't get first elf header of /usr/lib/debug/boot/vmlinux-x.x.x
> init_dwarf_info: Can't get first elf header of /usr/lib/debug/boot/vmlinux-x.x.x
> File eppic_macro/key.c, line 32, Error: Oops! Var ref1.[keyring_name_hash]
>
> This patch makes sure that clean_dwfl_info() is called once we are done with
> the debuginfo search.
>
> Signed-off-by: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>
It looks good to me.
I'll merge this fix into v1.5.4.
Thanks
Atsushi Kumagai
> ---
> dwarf_info.c | 58 +++++++++++++++++++++++++++++++++++++++++++++--------
> extension_eppic.c | 23 +++++++++++++++------
> 2 files changed, 65 insertions(+), 16 deletions(-)
>
> diff --git a/dwarf_info.c b/dwarf_info.c
> index a11b6ad..478d637 100644
> --- a/dwarf_info.c
> +++ b/dwarf_info.c
> @@ -1347,11 +1347,14 @@ get_die_nfields(unsigned long long die_off)
> tag = dwarf_tag(die);
> if (tag != DW_TAG_structure_type && tag != DW_TAG_union_type) {
> ERRMSG("DIE is not of structure or union type.\n");
> + clean_dwfl_info();
> return -1;
> }
>
> - if (dwarf_child(die, &child) != 0)
> + if (dwarf_child(die, &child) != 0) {
> + clean_dwfl_info();
> return -1;
> + }
>
> /* Find the number of fields in the structure */
> die = &child;
> @@ -1363,6 +1366,7 @@ get_die_nfields(unsigned long long die_off)
> continue;
> } while (!dwarf_siblingof(die, die));
>
> + clean_dwfl_info();
> return nfields;
> }
>
> @@ -1388,11 +1392,14 @@ get_die_member(unsigned long long die_off, int index, long *offset,
> tag = dwarf_tag(die);
> if (tag != DW_TAG_structure_type && tag != DW_TAG_union_type) {
> ERRMSG("DIE is not of structure or union type.\n");
> + clean_dwfl_info();
> return -1;
> }
>
> - if (dwarf_child(die, &child) != 0)
> + if (dwarf_child(die, &child) != 0) {
> + clean_dwfl_info();
> return -1;
> + }
>
> /* Find the correct field in the structure */
> die = &child;
> @@ -1408,6 +1415,7 @@ get_die_member(unsigned long long die_off, int index, long *offset,
>
> if (nfields != index) {
> ERRMSG("No member found at index %d.\n", index);
> + clean_dwfl_info();
> return -1;
> }
>
> @@ -1416,6 +1424,13 @@ get_die_member(unsigned long long die_off, int index, long *offset,
> *offset = 0;
>
> *name = dwarf_diename(die);
> + /*
> + * Duplicate the string before we pass it to eppic layer. The
> + * original string returned by dwarf layer will become invalid
> + * after clean_dwfl_info() call.
> + */
> + if (*name)
> + *name = strdup(*name);
> *m_die = dwarf_dieoffset(die);
>
> get_die_type(die, &die_base);
> @@ -1432,6 +1447,7 @@ get_die_member(unsigned long long die_off, int index, long *offset,
> */
> *nbits = *fbits = 0;
>
> + clean_dwfl_info();
> if (size < 0)
> return 0;
> else
> @@ -1455,21 +1471,35 @@ get_die_attr_type(unsigned long long die_off, int *type_flag,
> return FALSE;
> }
>
> - if (!get_die_type(&result, &result))
> + if (!get_die_type(&result, &result)) {
> + clean_dwfl_info();
> return FALSE;
> + }
>
> *die_attr_off = dwarf_dieoffset(&result);
> *type_flag = dwarf_tag(&result);
> + clean_dwfl_info();
> return TRUE;
> }
>
> /*
> - * Get name attribute given the die offset
> + * Get name attribute given the die offset This function is called by eppic
> + * layer directly as one of the callback functions.
> + *
> + * This function returns a pointer to newly allocated string which is a
> + * duplicate of original string returned from dwarf APIs. The reason for doing
> + * this is because the original string returned by dwarf layer will become
> + * invalid (freed) as soon as we close the dwarf handle through
> + * clean_dwfl_info(). This avoids the segfault when caller (eppic layer) of
> + * this function tries to access the string pointer.
> + *
> + * NOTE: It is callers responsibility to free the memory of new string.
> */
> char *
> get_die_name(unsigned long long die_off)
> {
> Dwarf_Die result;
> + char *name = NULL;
>
> if (!die_off)
> return NULL;
> @@ -1479,7 +1509,11 @@ get_die_name(unsigned long long die_off)
> return NULL;
> }
>
> - return dwarf_diename(&result);
> + name = dwarf_diename(&result);
> + if (name)
> + name = strdup(name);
> + clean_dwfl_info();
> + return name;
> }
>
> /*
> @@ -1510,6 +1544,7 @@ int
> get_die_length(unsigned long long die_off, int flag)
> {
> Dwarf_Die result, die_base;
> + int size = 0;
>
> if (!die_off)
> return FALSE;
> @@ -1519,17 +1554,22 @@ get_die_length(unsigned long long die_off, int flag)
> return FALSE;
> }
>
> - if (flag)
> - return dwarf_bytesize(&result);
> + if (flag) {
> + size = dwarf_bytesize(&result);
> + goto out;
> + }
>
> get_die_type(&result, &die_base);
> if (dwarf_tag(&die_base) == DW_TAG_array_type) {
> dwarf_info.array_length = 0;
> get_data_array_length(&result);
> - return dwarf_info.array_length;
> + size = dwarf_info.array_length;
> } else {
> - return dwarf_bytesize(&die_base);
> + size = dwarf_bytesize(&die_base);
> }
> +out:
> + clean_dwfl_info();
> + return size;
> }
>
> /*
> diff --git a/extension_eppic.c b/extension_eppic.c
> index a1981eb..d5e5ad0 100644
> --- a/extension_eppic.c
> +++ b/extension_eppic.c
> @@ -121,7 +121,7 @@ drilldown(ull offset, type_t *t)
> int type_flag, len = 0, t_len = 0, nidx = 0;
> int fctflg = 0, ref = 0, *idxlst = 0;
> ull die_off = offset, t_die_off;
> - char *tstr = NULL;
> + char *tstr = NULL, *tstr_dup = NULL;
>
> while (GET_DIE_ATTR_TYPE(die_off, &type_flag, &t_die_off)) {
> switch (type_flag) {
> @@ -201,9 +201,10 @@ out:
> if (fctflg)
> eppic_type_setfct(t, 1);
> eppic_pushref(t, ref + (nidx ? 1 : 0));
> - if (tstr)
> - return eppic_strdup(tstr);
> - return eppic_strdup("");
> + tstr_dup = (tstr) ? eppic_strdup(tstr) : eppic_strdup("");
> + /* Free the memory allocated by makedumpfile. */
> + free(tstr);
> + return tstr_dup;
> }
>
> /*
> @@ -216,7 +217,7 @@ apimember(char *mname, ull idx, type_t *tm, member_t *m, ull *last_index)
> int nbits = 0, fbits = 0;
> long offset;
> ull m_die, die_off = idx;
> - char *name;
> + char *name = NULL;
>
> nfields = GET_DIE_NFIELDS(die_off);
> /*
> @@ -243,8 +244,13 @@ apimember(char *mname, ull idx, type_t *tm, member_t *m, ull *last_index)
>
> if (!mname || !mname[0] || !strcmp(mname, name)) {
> eppic_member_ssize(m, size);
> - if (name)
> + if (name) {
> eppic_member_sname(m, name);
> + /*
> + * Free the memory allocated by makedumpfile.
> + */
> + free(name);
> + }
> else
> eppic_member_sname(m, "");
> eppic_member_soffset(m, offset);
> @@ -334,8 +340,11 @@ apigetval(char *name, ull *val, VALUE_S *value)
>
> if (!eppic_typeislocal(stype) && eppic_type_getidx(stype) > 100) {
> char *tname = GET_DIE_NAME(eppic_type_getidx(stype));
> - if (tname)
> + if (tname) {
> eppic_chktype(stype, tname);
> + /* Free the memory allocated by makedumpfile. */
> + free(tname);
> + }
> }
> return 1;
> }
>
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