Thread (22 messages) 22 messages, 3 authors, 2021-06-24

Re: [PATCH v3 07/10] mmc: handle error from blk_ksm_register()

From: Eric Biggers <ebiggers@kernel.org>
Date: 2021-06-17 03:25:23
Also in: lkml

On Fri, Jun 04, 2021 at 07:58:57PM +0000, Satya Tangirala wrote:
quoted hunk ↗ jump to hunk
Handle any error from blk_ksm_register() in the callers. Previously,
the callers ignored the return value because blk_ksm_register() wouldn't
fail as long as the request_queue didn't have integrity support too, but
as this is no longer the case, it's safer for the callers to just handle
the return value appropriately.

Signed-off-by: Satya Tangirala <redacted>
---
 drivers/mmc/core/crypto.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/mmc/core/crypto.c b/drivers/mmc/core/crypto.c
index 419a368f8402..cccd8c7d7e7a 100644
--- a/drivers/mmc/core/crypto.c
+++ b/drivers/mmc/core/crypto.c
@@ -21,8 +21,17 @@ void mmc_crypto_set_initial_state(struct mmc_host *host)
 
 void mmc_crypto_setup_queue(struct request_queue *q, struct mmc_host *host)
 {
-	if (host->caps2 & MMC_CAP2_CRYPTO)
-		blk_ksm_register(&host->ksm, q);
+	if (host->caps2 & MMC_CAP2_CRYPTO) {
+		/*
+		 * This WARN_ON should never trigger since &host->ksm won't be
+		 * "empty" (i.e. will support at least 1 crypto capability), an
+		 * MMC device's request queue doesn't support integrity, and
+		 * it also satisfies all the block layer constraints (i.e.
+		 * supports SG gaps, doesn't have chunk sectors, has a
+		 * sufficiently large supported max_segments per bio)
+		 */
+		WARN_ON(!blk_ksm_register(&host->ksm, q));
+	}
 }
There appear to be some MMC host drivers that set max_segments to 1, so this
explanation may not hold.  It may hold for every driver that actually supports
crypto, though.

- Eric
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