Change Details

isrc_alloc_irq() sets irq_next_free = maxirqs if the table is filled. Without these two lines allocations will never restart, and the system will be in serious trouble.

isrc_alloc_irq() had been allocating handles in order and scanning the whole table before failing. In case of failure irq_next_free was set to maxirqs to avoid repeated full scans of the table. Unfortunately isrc_free_irq() needed to reset irq_next_free and did not, hence once full allocations were permanently short-circuited. As the comment before isrc_alloc_irq() mentions, there is potential for a slow allocation attempt loop failure scenario. In this light, simply modify irq_next_free to always indicate the lowest available interrupt. Since irq_next_free can still equal intr_nirq the fast fail scenario still functions. A driver which tries to allocate two interrupts when only one is available (and frees the first during failure recovery) will be much faster since only part of the table will be scanned. This also simplifies the source code.

isrc_alloc_irq() sets irq_next_free = maxirqs if the table is filled.had been allocating handles in order and scanning the Without these two lines allocations will never restart, and the systemwhole table before failing. In case of failure irq_next_free was set to will be in serious troublmaxirqs to avoid repeated full scans of the table. Unfortunately isrc_free_irq() needed to reset irq_next_free and did not, hence once full allocations were permanently short-circuited. As the comment before isrc_alloc_irq() mentions, there is potential for a slow allocation attempt loop failure scenario. In this light, simply modify irq_next_free to always indicate the lowest available interrupt. Since irq_next_free can still equal intr_nirq the fast fail scenario still functions. A driver which tries to allocate two interrupts when only one is available (and frees the first during failure recovery) will be much faster since only part of the table will be scanned. This also simplifies the source code.