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| author | Will Deacon <will.deacon@arm.com> | 2012-02-24 11:25:21 +0000 |
|---|---|---|
| committer | Chris Ball <cjb@laptop.org> | 2012-03-04 12:25:14 -0500 |
| commit | 8f7f6b7e46117edb83d12a508fffa0f013457677 (patch) | |
| tree | eee70a97fd9f847c74c39200d347f8dc686c4245 /drivers/mmc | |
| parent | 5b6b0ad6e572b32a641116aaa5f897ffebe31e44 (diff) | |
| download | lwn-8f7f6b7e46117edb83d12a508fffa0f013457677.tar.gz lwn-8f7f6b7e46117edb83d12a508fffa0f013457677.zip | |
mmc: mmci: reduce max_blk_count to avoid overflowing max_req_size
On a system with large pages (64k in my case), the following BUG is
triggered in MMC core:
[ 2.338023] BUG: failure at drivers/mmc/core/core.c:221/mmc_start_request()!
[ 2.338102] Kernel panic - not syncing: BUG!
[ 2.338155] Call trace:
[ 2.338228] [<ffffffc00008635c>] dump_backtrace+0x0/0x120
[ 2.338317] [<ffffffc0003365ec>] dump_stack+0x14/0x1c
[ 2.338403] [<ffffffc000336990>] panic+0xbc/0x1f0
[ 2.338498] [<ffffffc00027a494>] mmc_start_request+0x154/0x184
[ 2.338600] [<ffffffc00027abdc>] mmc_start_req+0x110/0x140
[ 2.338701] [<ffffffc00028604c>] mmc_blk_issue_rw_rq+0x7c/0x39c
[ 2.338804] [<ffffffc00028652c>] mmc_blk_issue_rq+0x1c0/0x468
[ 2.338905] [<ffffffc000287564>] mmc_queue_thread+0x68/0x118
[ 2.338995] [<ffffffc0000bc308>] kthread+0x84/0x8c
This is because of a 64k request with a max_req_size of 64k-1 bytes.
The following patch fixes the problem by limiting the max_blk_count
such that max_blk_count * max_blk_size == max_req_size. I couldn't
pursuade the compiler to emit a shift instead of a div without encoding
the shift explicitly.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
Diffstat (limited to 'drivers/mmc')
| -rw-r--r-- | drivers/mmc/host/mmci.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c index 0d955ffaf44e..11e589cd8233 100644 --- a/drivers/mmc/host/mmci.c +++ b/drivers/mmc/host/mmci.c @@ -1271,12 +1271,13 @@ static int __devinit mmci_probe(struct amba_device *dev, /* * Block size can be up to 2048 bytes, but must be a power of two. */ - mmc->max_blk_size = 2048; + mmc->max_blk_size = 1 << 11; /* - * No limit on the number of blocks transferred. + * Limit the number of blocks transferred so that we don't overflow + * the maximum request size. */ - mmc->max_blk_count = mmc->max_req_size; + mmc->max_blk_count = mmc->max_req_size >> 11; spin_lock_init(&host->lock); |