Messages in this thread | | | Date | Wed, 25 Oct 2017 13:46:33 -0600 | From | Jason Gunthorpe <> | Subject | Re: [PATCH v2] tpm: use struct tpm_chip for tpm_chip_find_get() |
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> struct tpm_chip *tpm_chip_find_get(u64 id) > { > struct tpm_chup *chip; > struct tpm_chip *res = NULL; > int chip_num = 0; > int chip_prev; > > mutex_lock(&idr_lock); > > do { > chip_prev = chip_num; > > chip = idr_get_next(&dev_nums_idr, &chip_num); > > if (chip && (!id || id == chip->id) && !tpm_try_get_ops(chip)) { > res = chip; > break; > } > } while (chip_prev != chip_num); > > mutex_unlock(&idr_lock); > > return res; > }
?? The old version was correct, idr_find_slowpath is better than an idr_get_next serach if you already know id.
PrasannaKumar's solution seems right, if we already have chip, then we just need to lock it again:
struct tpm_chip *tpm_chip_find_get(struct tpm_chip *chip) { struct tpm_chip *res = NULL;
mutex_lock(&idr_lock);
if (!chip) { int chip_num = 0; int chip_prev;
do { chip_prev = chip_num; chip = idr_get_next(&dev_nums_idr, &chip_num); if (chip && !tpm_try_get_ops(chip)) { res = chip; break; } } while (chip_prev != chip_num); } else { if (!tpm_try_get_ops(chip)) res = chip; }
mutex_unlock(&idr_lock);
return res; }
Jason
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