Commit b5e8ad92 authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Mike Snitzer
Browse files

dm integrity: use init_completion instead of COMPLETION_INITIALIZER_ONSTACK 



The new lockdep support for completions causeed the stack usage
in dm-integrity to explode, in case of write_journal from 504 bytes
to 1120 (using arm gcc-7.1.1):

drivers/md/dm-integrity.c: In function 'write_journal':
drivers/md/dm-integrity.c:827:1: error: the frame size of 1120 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]

The problem is that not only the size of 'struct completion' grows
significantly, but we end up having multiple copies of it on the stack
when we assign it from a local variable after the initial declaration.

COMPLETION_INITIALIZER_ONSTACK() is the right thing to use when we
want to declare and initialize a completion on the stack. However,
this driver doesn't do that and instead initializes the completion
just before it is used.

In this case, init_completion() does the same thing more efficiently,
and drops the stack usage for the function above down to 496 bytes.
While the other functions in this file are not bad enough to cause
a warning, they benefit equally from the change, so I do the change
across the entire file. In the one place where we reuse a completion,
I picked the cheaper reinit_completion() over init_completion().

Fixes: cd8084f9 ("locking/lockdep: Apply crossrelease to completions")
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Acked-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Acked-by: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 7c373d66

drivers/md/dm-integrity.c

+10 −10
Original line number Diff line number Diff line
@@ -773,13 +773,13 @@ static void write_journal(struct dm_integrity_c *ic, unsigned commit_start, unsi 
	unsigned i;



	io_comp.ic = ic;

	io_comp.comp = COMPLETION_INITIALIZER_ONSTACK(io_comp.comp);

	init_completion(&io_comp.comp);



	if (commit_start + commit_sections <= ic->journal_sections) {

		io_comp.in_flight = (atomic_t)ATOMIC_INIT(1);

		if (ic->journal_io) {

			crypt_comp_1.ic = ic;

			crypt_comp_1.comp = COMPLETION_INITIALIZER_ONSTACK(crypt_comp_1.comp);

			init_completion(&crypt_comp_1.comp);

			crypt_comp_1.in_flight = (atomic_t)ATOMIC_INIT(0);

			encrypt_journal(ic, true, commit_start, commit_sections, &crypt_comp_1);

			wait_for_completion_io(&crypt_comp_1.comp);
@@ -795,18 +795,18 @@ static void write_journal(struct dm_integrity_c *ic, unsigned commit_start, unsi 
		to_end = ic->journal_sections - commit_start;

		if (ic->journal_io) {

			crypt_comp_1.ic = ic;

			crypt_comp_1.comp = COMPLETION_INITIALIZER_ONSTACK(crypt_comp_1.comp);

			init_completion(&crypt_comp_1.comp);

			crypt_comp_1.in_flight = (atomic_t)ATOMIC_INIT(0);

			encrypt_journal(ic, true, commit_start, to_end, &crypt_comp_1);

			if (try_wait_for_completion(&crypt_comp_1.comp)) {

				rw_journal(ic, REQ_OP_WRITE, REQ_FUA, commit_start, to_end, &io_comp);

				crypt_comp_1.comp = COMPLETION_INITIALIZER_ONSTACK(crypt_comp_1.comp);

				reinit_completion(&crypt_comp_1.comp);

				crypt_comp_1.in_flight = (atomic_t)ATOMIC_INIT(0);

				encrypt_journal(ic, true, 0, commit_sections - to_end, &crypt_comp_1);

				wait_for_completion_io(&crypt_comp_1.comp);

			} else {

				crypt_comp_2.ic = ic;

				crypt_comp_2.comp = COMPLETION_INITIALIZER_ONSTACK(crypt_comp_2.comp);

				init_completion(&crypt_comp_2.comp);

				crypt_comp_2.in_flight = (atomic_t)ATOMIC_INIT(0);

				encrypt_journal(ic, true, 0, commit_sections - to_end, &crypt_comp_2);

				wait_for_completion_io(&crypt_comp_1.comp);
@@ -1679,7 +1679,7 @@ sleep: 
	dio->in_flight = (atomic_t)ATOMIC_INIT(2);



	if (need_sync_io) {

		read_comp = COMPLETION_INITIALIZER_ONSTACK(read_comp);

		init_completion(&read_comp);

		dio->completion = &read_comp;

	} else

		dio->completion = NULL;
@@ -1840,7 +1840,7 @@ static void do_journal_write(struct dm_integrity_c *ic, unsigned write_start, 


	comp.ic = ic;

	comp.in_flight = (atomic_t)ATOMIC_INIT(1);

	comp.comp = COMPLETION_INITIALIZER_ONSTACK(comp.comp);

	init_completion(&comp.comp);



	i = write_start;

	for (n = 0; n < write_sections; n++, i++, wraparound_section(ic, &i)) {
@@ -2067,7 +2067,7 @@ static void replay_journal(struct dm_integrity_c *ic) 
		if (ic->journal_io) {

			struct journal_completion crypt_comp;

			crypt_comp.ic = ic;

			crypt_comp.comp = COMPLETION_INITIALIZER_ONSTACK(crypt_comp.comp);

			init_completion(&crypt_comp.comp);

			crypt_comp.in_flight = (atomic_t)ATOMIC_INIT(0);

			encrypt_journal(ic, false, 0, ic->journal_sections, &crypt_comp);

			wait_for_completion(&crypt_comp.comp);
@@ -2640,7 +2640,7 @@ static int create_journal(struct dm_integrity_c *ic, char **error) 
			memset(iv, 0x00, ivsize);



			skcipher_request_set_crypt(req, sg, sg, PAGE_SIZE * ic->journal_pages + sizeof ic->commit_ids, iv);

			comp.comp = COMPLETION_INITIALIZER_ONSTACK(comp.comp);

			init_completion(&comp.comp);

			comp.in_flight = (atomic_t)ATOMIC_INIT(1);

			if (do_crypt(true, req, &comp))

				wait_for_completion(&comp.comp);
@@ -2697,7 +2697,7 @@ static int create_journal(struct dm_integrity_c *ic, char **error) 


				sg_init_one(&sg, crypt_data, crypt_len);

				skcipher_request_set_crypt(req, &sg, &sg, crypt_len, iv);

				comp.comp = COMPLETION_INITIALIZER_ONSTACK(comp.comp);

				init_completion(&comp.comp);

				comp.in_flight = (atomic_t)ATOMIC_INIT(1);

				if (do_crypt(true, req, &comp))

					wait_for_completion(&comp.comp);

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